Me and PromedRick did the 242 series http://coord.info/GC3EH07 and I finished the day off with 100 finds that day. Around the lakes THEPASTOR http://coord.info/GC397CF has alot. We did 120 in a day up there and then Promed went back another day and did 180. The ELEMENT series http://coord.info/GC397CF out towards Katy could be done in a day or two Think its like 99 caches but what til it has not been raining. The Claps event http://coord.info/GC62A15 on the 12 would be one I would recommend. Wish I could go this year. Depends on where ya live, But Baytown has an nice little series I enjoyed doing another day we got over 100. BaytownBurts http://coord.info/GC2HQV6 .
Probably the best thing to do is "View the Geocaching Map" under Play on GC.com. There are several good series in your area and LOTS of caches in general. You should easily be able to get 20+ in a day without ever traveling very far from home.