This may be the most fun you will ever have flying. You are REQUIRED to fly 100 hours and there is no way around it. No other time in your career will a trip clear across the country and back sound practical or economical. Go anywhere you want and do anything, fly IFR, VFR and night and day and everything in between.
Me personally I did some mountain training and spent some time at the SoCal mountain airports. I had my tailwheel endorsement at the time so I flew the tailwheel for many of those hours because it was cheaper than a 172 but 10 times the fun.
If you have money to burn (unlikely) get your tailwheel endorsement and get a seaplane rating for a few of those hours.
Do not spend it doing 100 hours of pattern work or to the same old fields. Take advantage of it.