I did it on 8 toons for the whole duration, ended up with 2 mounts, and many medaillions/elixirs. The oil was pretty nice too. Been using the medaillions on my main to get the Trading Post rep to exalted without farming it (I already farmed it on another toon for the pet/mount but I want most reps exalted on main for those rep achievs when they happen every other expansion).
Not really doing anything special for the pet XP bonus event because I have every pet available and they're all maxed out (took about 2 years to do while doing other stuff). So mostly farming mounts in old raids and doing achievements, since my bank and storage are overflowing with gear already and need to wait until transmog update to start collecting that too.
I been using my hoarded gold to buy TCG mounts and to catch up on some of the older mounts I didn't have from jewelcrafting/engineering like the MoP panthers and the rockets. I'm still not decided on getting the 100K bike/yak and 50K riverbeast though... maybe when I'm much much richer and have no TCG mounts left to grab.
As for mounts, I'm done with Ulduar finally, took 272 runs but I got Mimiron's Head, now if I could get the drake off Deathwing to be done with Cataclysm. Still missing Poseidus and Aeonaxx but fuck camping for hours, I already did that once for time-lost and that was enough. I'm beginning to farm Throne of Thunder solo to get the mounts there, and already have MSV on farm solo to get that drake too.
Also trying to do PvP for those Nemesis achievements/titles but Ashran takes ages to get anything done, so it's slow-going.
Decided to do the Argent Tournament on my recent Horde toon also, to get all those mounts. So far I only had alliance toons ever since 2004 so it was about time to see the other side.
Once all that is done, still need to finish fishing for that turtle mount, and also wrap up archaeology pristine artifacts, about halfway done.
I'm definitely never running out of content, being a huge collection freak hah.