Hello Angela and Sabina,
I will go to Lombok Island and Bali on 13 - 17 May, because before May it's still rain season here in Indonesia, I got free voucher in Hyatt Sanur for 3d2n
, and I have travel book to Bali, Bali has 9 District : Badung, Denpasar, Gianyar, Bangli, Tabanan, Buleleng, Klungkung, Karangasem and Jembrana
I will spend 2 days in Lombok, hope I can go to Gili Trawangan and Senggigi Beach. then I will cross the strait to Bali, and hope can see the dolphin there. it said that if we want to see the dolphin, we have to go in early morning. and In Bali, Badung district is the must visit place than the others district. because it has so many vacation spot to visit. Don't forget to visit Garuda Wisnu Kencana (GWK), it has big statue of Garuda Bird and Wishnu, I was there on 2007, but the statue had not finished yet at that time. If you wanna hang out, come to Legian street. and enjoy Kuta for sunset... hmm I can's stand to go there 
You may visit Tanjung Benoa for Beach game (Diving, Flying fish, Banana Boat, and you can sail on cruise there..)
O yea, if you want to have seafood cuisine, don't forget to visit Jimbaran beach, you will find many seafood start from the cheapest up to the most expensive there..
Then.. visit Denpasar District for Museum, hmm and Get JOGER T-sHirt, it's very nice shirt to bring it home as a gift. and after that, you may go to Gianyar for shopping, go to Sukawati market, as traditional market. You may bargain up to 70% from the price they offer (I was get this secret from Balinesse guide) hehehe so don't be afraid to bargain, but once you bargain you have to buy. if you leave them after bargaining, they will angry to you.
Ubud is in Gianya district.. it's very very beautiful place.. with field scenery. and you may go to Tampak Siring palace. Bali Bird Park, Bali Safari & Marine, here you can have bubble walk.
O yea, for the ticket, please find on the internet, because if you buy the ticket at the spot, they will charge you higher price. BUt for Tourist they charge different price hehe.. so invite Indonesian people to join hahahah..
Hmm.. hotel, just visit hostel.com for backpacker budget, I suggest you to book hotel from Travel Agent, it will be cheaper than Hotel quote.
and about the transportation, i suggest you to rent car / motorcycle, because it bit difficult to find public transportation. or you may go with Taxi. so it would be better for you to go in group, you can share transport cost.
and don't forget to bring the veil / skirt while you enter the temple. if you don't you can rent Bali saroong there..
Well have a nice day in Bali..
just contact me for further info.