[Compact] PropertyDrawer. Makes Vector2, Vector3 and Quaternion display as non-foldouts, like in the default Transform inspector. Attribute in \Attributes, Drawer in \Editor.

CompactAttribute.cs

using UnityEngine;
using UnityEditor;

public class CompactAttribute : PropertyAttribute {

  public CompactAttribute() {}
	
}

CompactDrawer.cs

using UnityEngine;
using UnityEditor;

[CustomPropertyDrawer(typeof(CompactAttribute))]
public class CompactDrawer : PropertyDrawer {

  public override void OnGUI(Rect position, SerializedProperty prop, GUIContent label) {

		EditorGUIUtility.LookLikeControls();
		position.xMin += 4;
		position.xMax -= 4;

		EditorGUI.BeginProperty(position, label, prop);
		EditorGUI.BeginChangeCheck();

		switch (prop.type) {
			case "Vector3f":
				var newV3 = EditorGUI.Vector3Field(position, label.text, prop.vector3Value);
				if (EditorGUI.EndChangeCheck()) {
					prop.vector3Value = newV3;
				}
				break;
			case "Vector2f":
				var newV2 = EditorGUI.Vector2Field(position, label.text, prop.vector2Value);
				if (EditorGUI.EndChangeCheck()) {
					prop.vector2Value = newV2;
				}
				break;
			case "Quaternionf":
				var newV4 = EditorGUI.Vector4Field(position, label.text, QuaternionToVector4(prop.quaternionValue));
				if (EditorGUI.EndChangeCheck()) {
					prop.quaternionValue = ConvertToQuaternion(newV4);
				}
				break;
			default:

				EditorGUI.HelpBox(position, "[Compact] doesn't work with type '" + prop.type + "' (Supported: Vector2, Vector3, Quaternion)", MessageType.Error);
				break;
		}

		EditorGUI.EndProperty();

	}

	private Quaternion ConvertToQuaternion(Vector4 v4) {
		return new Quaternion(v4.x, v4.y, v4.z, v4.w);
	}
	private Vector4 QuaternionToVector4(Quaternion q) {
		return new Vector4(q.x, q.y, q.z, q.w);
	}	

    public override float GetPropertyHeight(SerializedProperty property, GUIContent label) {
       float extraHeight = 20f;
       return base.GetPropertyHeight(property, label) + extraHeight;
    }

}

Lots of extra height in there when it doesn't need to wrap, any idea how to fix?

Lots of extra height in there when it doesn't need to wrap, any idea how to fix?

Yes

// https://catlikecoding.com/unity/tutorials/editor/custom-list/
// https://gamedev.stackexchange.com/questions/122301/how-can-i-create-a-custom-propertydrawer-for-my-point-struct

public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
{
return Screen.width < 333 ? (16f + 18f) : 16f;
}