I would recommend Dark Tower if it is available: it is probably the best AD&D adventure I have ever seen - sort of like what Temple of Elemental Evil could/should have been. It has all sorts of cool traps, weird and dangerous adversaries (such as Haffrung Helleyes, a wizard who lives in the bodies of others) and plenty of action even for the most jaded dungeoneer.
There is also the Book of Treasure Maps series: three books with a collection of small adventures you can assign to treasure maps found in an enemy's hoard. The first one is the best, but you can find plenty of ideas from the others as well.
From the others, Citadel of Fire and Thieves of Fortress Badabaskor (cool title!) are the best I know of. They are both early JG titles, and they need some amount of rewriting for today's gamers, but the ideas inside are still solid gold (Badabaskor is the better one, Citadel of Fire is more developed though).
Last but not least, Ready Ref Sheets is indeed a useful play aid: I still use the random ruins table therein, as well as the taxation, mining and quest assignment guidelines. You can also use it to pretty much play the one true game (that is, OD&D) with it, as the booklet contains all attack and save charts, plus even a collection of all official OD&D monsters from the white box and its supplements!