You can't skip Pandora ads on Sonos (not even with UPNP commands), but you can mute them. This just watches for a Pandora ad playing and mutes the audio until the ad has finished. A much better approach is to just pay for Pandora.

SONOS Pandora Ad Auto-Mute

#!/usr/bin/env python
import soco
import time
import re

# pandora song:
# {u'album': 'Everything All The Time', u'artist': 'Band Of Horses', u'title': 'The Funeral', u'uri': 'pndrradio-http://audio-ch1-t1-2-v4v6.pandora.com/access/?version=4&lid=3729520&token=slyAWqqgjJ8Bl3TgMB%2F03C4tamOHsLj%2BOQLq1T8xbiwSzkcoc253HeYbNFTcOP7K6Oy9GOq6tcaManOhyKDpECIiCENj7hjBsH%2FJVhJnDjLzyPRWjg8q0LtX1mn80yFiurvB1r0G0Be76YBZJUswLdWtNZtfYSO2y2WdYHSge8Ul2hML1MWvkv23AQjw9%2BAKPmIHXX8nUzfcfFfLfmyKk%2Flxwh2cf%2BvDrJIbnnVZfvlfirWhshENZDm7BBofIlUqR0qsPXWbYN5m7WD4bS3XCK4dedE0QtHIlBaGvNIwNrorp3j5EoZM%2BybBEigsDXg%2B9To1w30%2BRbV8V3o6hyM5lpviYM4icmRBYVVjmA4hlWOE7aOFqcNAPA%3D%3D&a=http%3a%2f%2fcont-sv5-3.pandora.com%2fimages%2fpublic%2famz%2f0%2f2%2f0%2f9%2f098787069020_500W_500H.jpg&m=94f084d4cda66036692600d16036898d258a387c7a546916b33f7d907698ddf0e59d86721b571e2bfd793b4d25efc3cc856420f223031811&f=1&r=0&g=-5.93&x=000020aa', u'playlist_position': '4', u'duration': '0:05:22', u'position': '0:03:09', u'album_art': 'http://cont-sv5-3.pandora.com/images/public/amz/0/2/0/9/098787069020_500W_500H.jpg', u'metadata': '<DIDL-Lite xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:upnp="urn:schemas-upnp-org:metadata-1-0/upnp/" xmlns:r="urn:schemas-rinconnetworks-com:metadata-1-0/" xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/"><item id="-1" parentID="-1" restricted="true"><res protocolInfo="pandora.com-pndrradio-http:*:audio/mpeg:*" duration="0:05:22">pndrradio-http://audio-ch1-t1-2-v4v6.pandora.com/access/?version=4&amp;lid=3729520&amp;token=slyAWqqgjJ8Bl3TgMB%2F03C4tamOHsLj%2BOQLq1T8xbiwSzkcoc253HeYbNFTcOP7K6Oy9GOq6tcaManOhyKDpECIiCENj7hjBsH%2FJVhJnDjLzyPRWjg8q0LtX1mn80yFiurvB1r0G0Be76YBZJUswLdWtNZtfYSO2y2WdYHSge8Ul2hML1MWvkv23AQjw9%2BAKPmIHXX8nUzfcfFfLfmyKk%2Flxwh2cf%2BvDrJIbnnVZfvlfirWhshENZDm7BBofIlUqR0qsPXWbYN5m7WD4bS3XCK4dedE0QtHIlBaGvNIwNrorp3j5EoZM%2BybBEigsDXg%2B9To1w30%2BRbV8V3o6hyM5lpviYM4icmRBYVVjmA4hlWOE7aOFqcNAPA%3D%3D&amp;a=http%3a%2f%2fcont-sv5-3.pandora.com%2fimages%2fpublic%2famz%2f0%2f2%2f0%2f9%2f098787069020_500W_500H.jpg&amp;m=94f084d4cda66036692600d16036898d258a387c7a546916b33f7d907698ddf0e59d86721b571e2bfd793b4d25efc3cc856420f223031811&amp;f=1&amp;r=0&amp;g=-5.93&amp;x=000020aa</res><r:streamContent></r:streamContent><upnp:albumArtURI>http://cont-sv5-3.pandora.com/images/public/amz/0/2/0/9/098787069020_500W_500H.jpg</upnp:albumArtURI><dc:title>The Funeral</dc:title><upnp:class>object.item.audioItem.musicTrack</upnp:class><dc:creator>Band Of Horses</dc:creator><upnp:album>Everything All The Time</upnp:album></item></DIDL-Lite>'}

# pandora ad:
# {u'album': u'', u'artist': u'', u'title': ' ', u'uri': 'pndrradioad://http://t2-1.p-cdn.com/access/?version=4&lid=3729520&token=JWKN59qxNu2lJGzFLFmI4%2BbPJWonBt%2FM5B9I%2Bliu%2FUNPq7DkOKDU%2BjXEDimK4q3M5WlxBSaxUtp2Sa4tUbALw7FutSpYL6ndhgqeCSu3KOHm1gIHjg48lwngIcwbh1K9QBGUBAroEq2kep%2Fou977EuksnPUF1BbxRBLKziwUyfsDHgLvRADYtLiBDt2lwJb25X1kMCdrD%2BK4gEq7BUxLglha0VlsOB1MrhZmjcv8l8Tn0kFqAJiW6pY54e5f2MGueBFfCRL8bjKoYN99cZjsjPjfvBem5%2BfrGzsu%2FiN1VhNL3AzHo64Ytap1heZEER6wmcneMSj3PsvSKKRmlZYrmh3nCY%2F7s5VYZdqvpMKfLNs%3D&a=http%3a%2f%2fcont-1.p-cdn.com%2fimages%2fpublic%2fdevicead%2fs%2fm%2f2%2fr%2fdaarv2190082q3r2ms_500W_500H.jpg&m=ADU-3729520-6-15520-none-0-1423412705129%3aADU-3729520-6-15520-none-1-1423412705130%3aADU-3729520-6-15520-none-2-1423412705130&f=0&r=0&g=0.000&x=000020aa', u'playlist_position': '3', u'duration': '0:00:16', u'position': '0:00:03', u'album_art': 'http://cont-1.p-cdn.com/images/public/devicead/s/m/2/r/daarv2190082q3r2ms_500W_500H.jpg', u'metadata': '<DIDL-Lite xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:upnp="urn:schemas-upnp-org:metadata-1-0/upnp/" xmlns:r="urn:schemas-rinconnetworks-com:metadata-1-0/" xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/"><item id="-1" parentID="-1" restricted="true"><res protocolInfo="pandora.com-pndrradioad:*:audio/mpeg:*" duration="0:00:16">pndrradioad://http://t2-1.p-cdn.com/access/?version=4&amp;lid=3729520&amp;token=JWKN59qxNu2lJGzFLFmI4%2BbPJWonBt%2FM5B9I%2Bliu%2FUNPq7DkOKDU%2BjXEDimK4q3M5WlxBSaxUtp2Sa4tUbALw7FutSpYL6ndhgqeCSu3KOHm1gIHjg48lwngIcwbh1K9QBGUBAroEq2kep%2Fou977EuksnPUF1BbxRBLKziwUyfsDHgLvRADYtLiBDt2lwJb25X1kMCdrD%2BK4gEq7BUxLglha0VlsOB1MrhZmjcv8l8Tn0kFqAJiW6pY54e5f2MGueBFfCRL8bjKoYN99cZjsjPjfvBem5%2BfrGzsu%2FiN1VhNL3AzHo64Ytap1heZEER6wmcneMSj3PsvSKKRmlZYrmh3nCY%2F7s5VYZdqvpMKfLNs%3D&amp;a=http%3a%2f%2fcont-1.p-cdn.com%2fimages%2fpublic%2fdevicead%2fs%2fm%2f2%2fr%2fdaarv2190082q3r2ms_500W_500H.jpg&amp;m=ADU-3729520-6-15520-none-0-1423412705129%3aADU-3729520-6-15520-none-1-1423412705130%3aADU-3729520-6-15520-none-2-1423412705130&amp;f=0&amp;r=0&amp;g=0.000&amp;x=000020aa</res><r:streamContent></r:streamContent><upnp:albumArtURI>http://cont-1.p-cdn.com/images/public/devicead/s/m/2/r/daarv2190082q3r2ms_500W_500H.jpg</upnp:albumArtURI><dc:title> </dc:title><upnp:class>object.item.audioItem.musicTrack</upnp:class></item></DIDL-Lite>'}

def isPandora  (uri): return uri.startswith("pndrradio")
def isPandoraAd(uri): return uri.startswith("pndrradioad")

# take the hours:minutes:seconds (e.g. 0:03:12) format from the soco/pandora
# library for duration or position values and convert into raw seconds
def hmsToSecs(hms):
    m = re.match(r'([0-9]+):([0-9]+):([0-9]+)', hms)
    if m:
        return int(m.group(1))*60*60 + int(m.group(2))*60 + int(m.group(3))
    else:
        return 0

if __name__ == '__main__':
    # store the old volume for the zones that are currently being paused
    # because o0
    # zone was (no longer) being paused by us
    pausedZones = {}

    debug = True

    while True:
        try:
            if debug: print("Checking zones.")

            # for each playing zone find the one with the smallest amount of seconds left until the current track ends
            minTrackSecsLeft = 240

            for zone in soco.discover():
                playing = zone.get_current_transport_info()['current_transport_state'] == 'PLAYING'

                if debug: print("Checking: %s (%s)" % ( zone.player_name, zone ))
                #if debug: print("    %s" % ( zone.get_current_transport_info() ))

                if not zone.is_coordinator: continue
                if not playing: continue

                current = zone.get_current_track_info()
                uri = current['uri']

                #if debug: print("    URI: %s" % ( uri ) )
                print("    Current Track: %s (%s) / %s" % ( current['title'], current['album'], current['artist'] ) )

                if not isPandora(uri):
                    if debug: print("    Zone is not playing a Pandora radio station. Skipping.")
                    continue

                dur = hmsToSecs( current['duration'] )
                pos = hmsToSecs( current['position'] )
                minTrackSecsLeft = min(minTrackSecsLeft, dur-pos)

                if debug: print("    Current position: %s / %s ( %d s )" % ( current['position'], current['duration'], dur-pos ))

                # no longer an ad and we'd previously muted this zone
                if not isPandoraAd(uri) and zone.player_name in pausedZones and zone.volume == 1:
                    if debug: print("    Zone is muted and ad has finished. Unmuting.")
                    zone.volume = pausedZones[zone.player_name]
                    del(pausedZones[zone.player_name])

                # ad is playing, volume isn't muted - take the current volume and store it then mute
                if isPandoraAd(uri) and zone.volume > 1:
                    if debug: print("    Zone was not muted and ad is playing. Muting!")
                    pausedZones[zone.player_name] = zone.volume
                    zone.volume = 1
        except Exception as ex:
            if debug: print(ex)
            pass

        sleepTime = min( 30, max( minTrackSecsLeft-2, 1 ))
        if debug: print("Zone with the next ending track has %d seconds left. Sleeping for %d seconds." % ( minTrackSecsLeft, sleepTime ) )
        time.sleep(sleepTime)