Is the AC worth the money over an N?
Depends what you want to do. If you're browsing the net and the heaviest thing you do is watch Netflix, an N16 will do you fine. I use one at home, and it's good enough for me but regularly moving around TB of data is taxing it. I'm replacing it with RT-AC68U. I have one at work that's within arm reach.
AC has two things, beefier CPU and generally USB3 port(s). Well, and AC speed, obviously. You can use the Asus router as a makeshift NAS, by plugging in an external hard drive. If you want to do this, USB3 is pretty important. If not, not a big deal. Beefier CPU is only necessary if you plan on having complex router configuration. VPN, complex filtering rules, using it as a print server, using it as a NAS. If you're just going to use it as a router with near default config, get the N. If you plan on doing wild and crazy stuff, get the AC.
I think the N will be just fine. I think an N16 will suit your needs, but the N66U will do you fine. AC68U is definitely overkill for your needs, probably. Let me know if you need dimensions, power usage, speed testing or whatnot.