No proper recommendations from me, sorry. I've only been to Witches Point on the Gower and there wasn't any good routes in the low sixes. There are routes there if you're struggling to find something though.
I'd recommend that you use the 'find crags' feature in the logbooks section to find something. If the routes have two or three stars they are probably half decent. Good luck.
Your best bet would be to go to Southgate area on Gower, good mix of sports climbs. Watch House Slab has good mix of grades 5's and 6's with some great 6b's. Also close by is Foxhole for some harder steeper stuff. Info can be found on SWMC wiki (google it) or alternatively my new guidebook covers this 'Gower Rock'. Book is available from the Three Cliffs Coffee shop at Southgate if your interested.
A group of us are heading to Foxhole on Saturday. Maybe see you there! Hope you have a good time.