I would recommend getting a set group that you play with every day (or 5 days a week or 3 days a week or whatever).
With POR Sony has finally filled in all the gaps so that groupers, strictly from 1 groupable equipment and bazaar equipment, can get all the way to RSS. One progression would be NC (levels 65 -> 70, plus 66-68 spells and some OOW tier 1 armor), RCOD and WOS cubbies, then POR quests especially including the spirit armor quest, then DoD missions, then finally MPG and RSS. MPG can probably be started earlier somewhere but there is no reason to fight there unless there are camps for 69 and 70 spells (I have yet to see any 69 or 70 runes drop in MPG, though I have seen 69s drop from the cubbies in WOS). [Note - there are also some nice equipment drops like Soul Imbued Rings to get from MPG as well, but mostly I have been disappointed in the reward part of MPG] [Since I can get my runes from RSS and my equipment upgrades from other areas I could care less about MPG - it's just a transit zone for me now].
But you pretty much need to find a steady group. 1 tank, 1 cleric (for rezzes if nothing else), 1 shaman, and 3 others. A chanter bot for c3 and a druid bot for 9/10 and you are good to go. Actually no need for the chanter bot anymore - just get alchemy up to around 180, get the alchemy trophy item for the increased alchemy skill mod, and for each nodding blue lily you can get your hands on from Old Sebilis you'll be able to make 2.5 (approximately) c3 potions. Or for a group of 6 that would be a bit more than 2 lilies per half hour of c. So over time thats a fair amount of farming in Sebilis ... on the other hand Sebilis is a pretty fun zone to kill in even for a high level group and the drops can get you some good pp to boot so maybe your full group can spend some farming time there to get the nodding blue lilies for c potions.
With a steady group, starting from level 65 and getting to 70 with a bunch of AAs would provide maybe a year or so of good solid fun and enjoyment as you progress from NC to RSS. This is exactly what Everquest is when Everquest is at its best. It is doable and fun and the friendship part of it completely rocks
And if you are level 60-65 now this progression would require not even 1 purchase of any future expansion to accomplish all of this if that were desired.
Without getting such a group I am not sure what to advise. I am sure there are people that get to high levels via soloing and pickup groups. But that sure seems like a hard road to hoe to me. Its hard enough with a solid group to depend on! Everquest is also loads more fun when it is shared with friends. For groupers Everquest is now in its Golden Age. However it seems to pretty much require having a set of 6-8 people (or 3-5 if there is a lot of 2 boxing going on) that you can group with on a very regular basis.
Having a set group is also good for the pocketbook. I will be spending on the order of 150k pp on alts over the next week. I could never have made that kind of dough soloing/pickup groups. Our MT recently spent 380k pp on his GM cultural armor chest and legging items, including augments. WOS Cubbies is one of many nice places to farm for pp for us. With a set group farming for pp is fun and actually pretty easy.