Lydian scales have a nice jazzy sound over major 7th chords. A lydian scale is a major scale with a raised 4th, like starting at F and playing all white keys.

In C, a lydian scale is C D E F# G A B C

Likewise, a maj7#11 (like C E G B F#) has a nice jazzy sound. Also maj9#11 (like C E G B D F#).

PA