I have checked in for 3 nights at Portofino bay Hotel at universal for the 4th July, That give us front of line passes for the period of the stay. Therfore it doesn't matter how busy the parks are. The atmosphere should be great.
Even if you book just one night you can use the room key for 2 days, the day you arrive and the full day after you check out. It would be about $250 for the night but is well worth it. You can have a drink in the parks or City walk, Watch the fireworks and take the water taxi back to the hotel.