Agreed on the FFXI OST being fan-fucking-tastic - I still fire it up on occasion, and it's still a nostalgia trip every time.
As for resubing, I've gone through a few bouts of it. Early on, the group of people I played with never managed to stick with the game very long, and we ended up switching servers (and restarting) several times when we'd inevitably come back to the game. My last two attempts at going back were solo efforts, so at the very least I was able to hop back on an old character and not completely start from scratch.
The first of those was shortly after Wings of the Goddess came out. I logged in, in Mhaura, and decided to head back to San d'Oria to get my bearings. Waited however long for the boat, boarded what turned out to be the Aht Urghan boat, waited for the trip back, waited for the other boat, finally got back to Selbina, and then said fuck it and logged.
My most recent return was a very different affair, sometime after the release of all the Abyssea stuff, and I probably had the most fun with the game here. With my mid-30s Monk/War I spent some time unlocking the rest of the jobs I didn't get around to previously, as well as the new stuff since I had last actually played (except Scholar - never been a big fan of casters and just didn't get around to it). I decided to give Dancer a go, and it completely changed my outlook on the game - between the ability to efficiently solo and the repeatable Page quests (don't recall the exact name), I was capped at 50 in no time. I then switched over to a Dancer sub and easily (and quickly) leveled almost all of the other melee classes to 50 (I think I left Samurai somewhere around 40, and hadn't started Ninja yet), either solo or in mass dungeon page-parties, and did a good chunk of the rank progression stuff solo. I was in the process of soloing the stuff for the level 50 limit break (I was having issues with the Bombs in Garlaige iirc) when something else came out I was interested in playing... I think it may have been Mists of Pandaria.
I do have to admit, between the lack of any enticing MMOs to play at the moment, and the wait for Realm Reborn, I've been tossing the idea of resubing again around.