I completely forgot to update this. We ended up going to NYC, saw America's Got Talent and drove through the night until morning, we missed all the DC traffic which was my main concern - stopped at a Waffle House in Wade, NC. The drive continued, stopped for the day in Savannah, Georgia at the Best Western ($40 for 4 people, just outside of downtown) with breakfast and a decent pool. Went downtown, ate at Outback and walked the shops a bit, slept and left the next morning. The drive continued, got pulled over by a state trooper on I-95 in Florida going 93 in a 65. Cut us a break, said it was 79, nice cop. At the border, there was a sign for Orlando tickets, $39 a ticket. We missed the exit for the welcome center so couldn't stop off.
We got to Coconut Grove the same day, which is where we were staying, went to a Cheesecake Factory in the area, walked around town then crashed for the night. Next day was South Beach - unplanned but definitely the best day of the trip. Went on the beach (beautiful beach, perfect water), shopped a bit, friends rented a moped, went to dinner at a place called The Sugar Factory (it's not what it sounds like), had a fantastic meal with a fantastic waitress. Got served an alcoholic beverage without getting carded (none of us were 21, waitress was just awesome), had filet mignon & lobster afterwards. Stayed out a bit longer for the nightlife then back to the hotel. Third day was next to nothing, stayed at the hotel pool and relaxed. Planned out the rest of the vacation a bit and decided to leave a day early to do Disney world, Seaworld or Port Canaveral. Ultimately, none of that happened, the others ran out of money. Final day (#4 in FL) went to the Miami Zoo. Tickets were cheap but it was nothing spectacular. Tickets were $13, whereas Seaworld tickets (or anything in Orlando was at least $60+ p/p). Stayed at the hotel for the night and leave by noon. It took 7+ hours to get out of Florida. Drive straight through to get back, unfortunately didn't do anything at South of the Border or Blue Ridge Parkway - it was midnight for SOTB and far too late for Blue Ridge. Hit minor traffic in DC, nothing awful. Accidentally stopped off at a GM Operations plant in Baltimore, saw an oil rig in the back but just stayed in the parking lot. Got back to the house around 5pm the next day, straight through, no hotel.
Ultimately, would I do it again? Yeah, but with different people. Tough having a good time when #1 you can't make everyone happy and #2 the others have serious money constraints. My brother (the business owner) and I are either planning a two night stay to Times Square or go down to Myrtle Beach, SC with stops at the OuterBanks, South of the Border and Blue Ridge Parkway. Sorry for long block of text. May post some pictures.
Oh, forgot to mention: thunderstorms were expected every day for the length of the trip. We hit some awful weather while on I-95 but no storms during the stay in Miami.