Depending on where you're going to.....
Hubby and I had a great time on the Paranormal Tour on the Queen Mary which is docked at Long Beach (Calif). I put a post on here somewhere about my experiences on it and the spirit I met. (Plus they serve a delicious clam chowder and other lovely things in the dining room - if you get a chance before the tour). You can actually stay on board if you like. It's a hotel also.
Pearl Harbour also has a few places where there is lots of 'energy', but no actual 'ghost' tours. Your paranormal experience there would depend on what you can 'pick up' yourself, personally, regarding spirit energy. You can wander through a submarine, and wander all over the Missouri Battle Ship, plus go out to the place that's directly above the ship where all the crew still lie entombed. The top of the ship is just below the surface. There's a spot on the side barrier of the Missouri where a Japanese Kamikase pilot slammed into it. Obviously, Pearl Harbour is more wartime essence. Like Gettysburg in that sense.
What I'd suggest is that you check out the other paranormal sites for the United States and check out what evidence they've come up with during their investigations. I'd do that because it gives you an idea of what to expect and whether you could be wasting your time on particular ghost tours.
Also there's the actual paranormal/ghost tour sites to check out. I'd just be wary of what's on offer however, as they do have a flair for Hollywood style things over there, and its possible to pay heaps of money to waste your time.
I haven't been to Vegas, so I can't comment on it really. As for the east coast, there are lots of historical places in that region, with ghost tours at some of them. IMHO the east coast of the US is a far more interesting region and has some great history.
A member here recently posted about visiting Gettysburg. They live not far from there and go there almost every weekend.
Another suggestion, some places are heavily booked, depending on the season, so you might want to book the ghost tours before you leave Australia. For example, when we went to Scotland in 2007, we booked for the tour of the Haunted Vaults beneath Edinburgh - before we left Australia. If we hadn't booked, we would not have got on a tour at the time we were there. I'd imagine that places in the US would be just as heavily booked.
