Thanks guys. I would have made the bench about 3x the length, but I had to compromise. It's a small garage in a townhome and it won't be my home for many years. I also need some room along the side for an air compressor.
Finished length of the top came out to somewhere around 76", and it's plenty deep with that ~2" overhang I left on the front various projects requiring clamps.
As this was my first real wood project, I did learn a lot. I mostly learned as I went, made mistakes and corrected them when I wasn't 100% happy, and made sure I considered everyone's input in this thread. I also considered various scenarios I'd run into while using the bench, and tried to avoid as many future regrets as I could.
As many have stressed, always plan to anchor your bench into the structure where you can. It makes the world of difference as far as rigidity. It really breaks my heart to see a flimsy foundation for presses and vises where the tools work against you. On that subject, a solid wood core commercial interior door makes for an awesome benchtop if anyone's on a budget. It's smooth, straight, rigid, easily replaceable, and far cheaper than two sheets of plywood glued and screwed together.