We are staying at the DLH for the first time next month. I've been reading here that everybody recommends getting into the Dreams (formerly Sierra) Tower. Why?
If you get the side overlooking Downtown Disney, you'll have a nice view of DDD with glimpses of both parks, plus you can watch the fireworks from your room.
Around 8:30ish pm, go to your room. Get comfortable. Order up some food and a bottle of champagne. Open door to window. Watch fireworks while sipping and eating in bed. That's why I enjoy the Dreams Tower.
The Sierra/Dreams tower is the only tower with nice views on BOTH sides. You'll either have a view of DTD/fireworks/themeparks.....or.....you'll have a view of the Neverland pool.
I haven't stayed in Sierra Tower, and while it does look very nice, I loved the Marina Tower, too. It's so close to everything and right off the hotel lobby. We had the pool view which was fabulous--Tinkerbell was somehow "beamed" into the pool on some nights. I would be happy with either tower.
I've stayed in both sides of the Bonita Tower and that would be my last choice. It just has a feel of being an afterthought as far as service and convenience go.