The three Leaning House CDs are the ones to get. All are good.
The Timeless recording with David Newman mostly (to my ears) doesn't gel.
There's not really that much of him on record, alas.
I saw him quite a few times over a number of years (starting about 1974), but didn't really take advantage as much as I should have.
A few favorite experiences:
One of my first jazz concerts, with James Clay at the Recovery Room.
Back around 1976 or so, alternating sets with Freddie Hubbard's band.
At the Caravan of Dreams, for the second set Cornell Dupree came out and played guitar with Marchel's band.
At a Theater in Fair Park, a double bill concert with Marchel's band and David Fathead Newman, concluding with the two tenors playing together.
At the Caravan of Dreams, a couple of cameo appearances--sitting in with Art Blakey for the last song of his engagement--and another time, sitting in for a song with McCoy Tyner.
On the SMU campus, after a lackluster Wynton Marsalis small group concert, I'll give credit to Wynton for bringing Marchel up to the stage for the last song and injecting some fire into the otherwise dull evening.
And at the shortlived Jazz Connection, with Joey DeFrancesco.