Well, its possible to spend LARGE portions of 1-60 killing just Undead.

personally when soloing, i try to stick to dungeons cuz of the zem

but heres a rough outline for out door soloing, 1-10 your noob zone
14-25 ek is great, but for 10-20 you can do oasis
20-30, sk isnt bad, but can be overcamped, or head to loio, so much to do here
30-40, for a necro id say the ovethere, or fv if ot is too camped
40-50 any guards, dread lands
50+ i am not sure yet, havnt reached these lvls quite yet

but for a duo, or you think yer powerful enough for these dungeons, 10-20 kurns (great duo place and pretty much safe), unrest 15-30, plenty ol of em undead, 25-30 you can do hhk, 30-40 or maybe higher kaesora, at 43 ive soloed quite a bit here, though it is all close quarters, you can run into trouble if you dont take it a bit slow, 40-50 im not too sure

hope this helps

Love your Avatar; FFT rules. Also love this statement.

Which is part of why I made that big post about class balance weeks ago - the game doesn't allow you to do things like that in the higher level content (not talking about epic level here). It instead becomes exactly the opposite and you are very much limited to rather specific setups if you want to engage in that content.

At the lower/mid levels I've seen all kinds of interesting class combinations be able to work together and accomplish something relevant. Can that happen at the higher levels, though? Nope. Instead of getting to be creative and think of how you can make what you have feasible, at least in some manner, you are locked into NEEDING specific setups to even play. Unless your idea of "playing" is 15+ minutes of downtime for 1 mob.