I'm thinking about knocking out a PDK life and a few Shadar Kai, plus I need to put a dent in my martial sphere - so I'm thinking 2 epic lives then an IR. 

I'm thinking staff or crossbow builds since I've got those laying around or a great axe build (trying to avoid having to farm extra gear for just a few lives).

I really, really, really don't want to do handwrap monks.  I know they're OP and all, but I found them kind of boring.

So what's a good build to knock out my martial sphere?

Not done my own pdk yet, but I guess almost anything may work, fighter is great class for splash, even 1 level of it gives you a feat, all armor and most weapons prof. Pdk racial tree is very human-like, thats good also.

For shadar-kais I did both xbow shooter and 12-8 monk/rogue.
Shooter was decent cause of angle and nothing good in racial tree but 2xSA. No int again.
12-8 splash is something I enjoyed. The only issue is there no any good staff for lower epics and heroic elemental bloom is totally bad for epic content. Yet once you hit 26 and equip epic one it'll gonna be truelly easy power creep. 12-8 is for monk pastlife obviously, 8 rog cause of improved uncanny and 12 monk to take 1 more henshin core and waste only 1 feat for grandmaster of forms. Both monk paths are interesting for henshin: with light you'll be able to put aoe neglevels, with dark you'll spamm aoe heals. For henshin both finishers are avaible.
Start with 13 str(+4 tome) 18 dex rest in con, may want 10-12 int for trap skills.
1 power attack
3 cleave
6 gr cleave
9 thwf
12 imp crit blung
15 imp thwf
18 gm of forms
Monk
1 dodge
2 mobility
3 spring attack
21 overwhelming crits
24 greater thwf
27 epic dr
30 precision

26: guardian angel
28: perfect thwf
29: dire charge

I dont clearly rememver my enchantments splash, but it was surely t5 henshin, so 36 min here, TA at least 22, you wont miss shadow dodge and extra dex. For rest you may go whenever you want, extra SA dices always good if you manage to do sneaks, may want skills action boost or passive bonus cause of fairly low int, racials for aoutosearch (pretty bad choice though, but sometimes worth, say, in schemes or prove your worth, strahd).

Pros: easy button, good aoe damage, possible heals spam, very good solo ability if geared, can do traps, easy 100% dodge on uncanny.
Cons: no CC till 29 (at 26 epic elemental bloom procs are pretty good though) terrible lay waste DC ( you may not want to use it at all), decent ac cause of lacking wis, dodge or die in some situations on reaper.