Search and Destroy

Here is a list of what I have, since I should be working on an army list, I guess. I am willing to spend a little more, but no crazy 8 Immolator lists for me, sir. Any suggestions?

Four Immolators/rhinos
One Whirlwind sprue
Two Penitent Engines
10 Seraphim (7 pistols, 2 flamer pistols, 1 VSS w/ Eviscerator) mounted on resin bases
2 Sisters w/ Melta
2 Imagifiers
1 Sister Superior w/ Combi-Melta
3 Sisters Superior w/ Bolter and Icon (I forgot what they are really called, but if you play Sisters, you know the model I mean)
1 Sister Superior w/ Chainsword and Plasma Pistol
1 Canoness w/ Book and Chainsword
1 old Canoness w/ Icon and Combi-Flamer
3 Sisters w/ Hvy flamer
2 Sisters w/ Hvy Bolter
1 Sister w/ Multi Melta
1 Sister w/ broken Multi Melta
3 Sisters w/ Storm Bolter
3 Sisters w/ Flamer
45 Sisters w/ Bolters

I'm planning, in the very least, to pick up a Priest, so I can field the Penitent Engines some day, even if they do not make the every day list. Same goes for at least 1 more Rhino, since I can use the bitz I have to make it an Exorcist. One purchase not on the itinerary is a Repressor. The model is nice and all, but I am looking for a fairly standard list with no wobbliness, rules wise. Also, I am not exactly an ace convertor, so I likely won't be giving all my Sister Superiors the book of St. Lucius, unless it is really ace and I am told of a super easy fix. So, give me your suggested lists, be it horde, mech, or some combination. Winning list gets, um, a Canoness named after them.