A great many 65's have days of played time in any one of several popular zones. Akheva, probably Seru, Greenhills (for me, soloing as a bard), ToV, the ever present Necropolis, and Sirens,etc.
Of bigger concern to me is the lifespan of this xp bonus/penalty system. At some point, nearly ALL decent places to get aaxp will be pummeled into the neg xp side of the scale and be very slow on the xp. I know this system was designed to encourage us to explore and enjoy the rest of the content the dev's worked so hard to put in. And by and large it has. But in the end, after we've gone all neg xp in perhaps every zone we could, what then? Some will leave at that point, because of the boredom? Or is it believed by the devs that before we went nex xp in all high xp zones, we'd already have max aaxp? I know I wouldn't, not at my pace. I'm on alot, but xp doesn't always flow quickly. And my soloing time is slower yet.
Food for thought, enjoy the meal. Peace.