^ I agree, Medewi/Balian if your chasing something mellow. Maybe even Berawa on a mid to low tide. But I'd forget Ulu's unless your already fit & at least a fairly good surfer coz its always busy when its on. There are plenty more waves up the North West coast to offer more challenge. If your only going for 6 weeks I'd stick to Bali/Lombok & leave Java for next time coz travelling round there can be a bit of a challenge itself unless your just jumping on a boat at Tuban & heading to G-land along with the rest of the July-August masses.
Alternatively you could stay at Slim's place in Tuban baliwaves.com Very good value considering you get accomodation in a good location within easy reach of waves catering to pretty much all conditions, advice on where to go based on your skill level, transport & photos. I just got back from 2 weeks in Bali today & bumped into Ketut & Pat who's staying at Slim's at the moment (had guest house to himself). He's the bloke with the orange boardies in the pics over the last 2 weeks or so. There's a pic of me barreled, 2nd last pic on the 7-8 Jan