I would say that the NewEgg reviewers say to pick the WRT54G over the WRT54GL if you want to use the stock firmware merely since it's cheaper. The extra RAM/flash (the difference between the G and GL) is more useful for Tomato, DD-WRT and the like. Simple as that... I would guess the stock firmware is largely identical between the two.

My WRT54G seems to be having hardware issues so I'm in a similar position. I'd be looking to get two N devices. An access point and a client bridge since I use it to make my MythTV box accessible. HD can't stream over 802.11g even with good signal strength.