did this last year pretty last minute (like 4-5 days before we left we booked) and had a blast. we were able to use g/fs dads rewards points and score a free night at a hotel, so we paid the same for a hotel right on the strip as we would have for a hotel 8 miles from the beach. walked across the street and was at the beach.
when you go, just sit out on the beach the night of the 4th. people will be lighting off fireworks all night long. i dont know the legality of them there, but people dont seem to give a shit.
and if you like to fish, take a couple big rods out there, and head to the pier, get some double hook rigs, a heavy weight, and some squid, and throw your line out as far as you can off the beach...after dusk, you'll pull in doubles of little sand sharks all night long. its a blast. theres pics of the ones i was catching last year somewhere here