I'm assuming you need wireless for practice tests. Some of my study hang-outs are:
-Salentos in the village (closes at 10pm, no wireless after 6pm on wed/sat, also it can be a bit loud sometimes - not the best for practice tests)
-the starbucks on shepard close to richmond (unprotected wireless), very quiet and people are mostly studying
-crossroads in the village (i think they close at 10, 11 on weekends)
-there's a 24hour starbucks on westhiemer at the galleria, not sure about wireless at that one though, and i've never been so i don't know if it's quiet
-you can try the student center at Rice (i'm there right now...) as well or the jones business school at Rice (but I'm not sure if their hours would be better than those of the Rice library)
-annie's is a cute place - it's in the village on the corner of morningside and university - looks like a residential house - very cute and quiet, but they close at 6pm
-i've also studied at restaurants such as the black walnut cafe(rice village), they have a quiet corner near the back, and if it's not hot outside is nice
Good luck! I'm leaving on tuesday to take the MCAT in Dallas... you can take over my spot at these places 🙂