What are your interests? Frankly, the USS Liberty can hardly be considered a wreck anymore (although it still attracts hordes of divers with poor buoyancy skills. There can be (at least for me) some interesting life like frog fish that can be spotted, if the previous swarm of divers hasn't scared them off. For me, the attraction of Tulamben is the incredible macro life that lives in the black sand slopes. For me, four days is more than enough time to hit all the good spots.A follow-up question - if I wanted to do some days on Tulamben and some on Lembongen (where so far I have seen recommendations for Big Fish and for World Diving) - would say 4-5 days in each be appropriate? Or more for one or the other? They seem fairly reachable from each other but as I understand it each has different attractions?
Sorry if these are dumb questions - although I have dived elsewhere in Indonesia a few years ago (Bunaken, Lembeh, Raja Ampat) I have never been in the Bali area before..
If you're a fan of walls, Pemuteran to the North is quite nice. I would enthusiastically endorse Sea Rovers (small fast six-pac boats)