A largish, soft lump on my butt cheek isn't bothersome, but if it needs surgical excision, what are practical considerations for stitches, etc.?

Soft tissue lump: This is most likely a lipoma but it is best to have it examined by your PCP to confirm. Dependent on where it is located on the buttock - pressure from sitting can sometimes cause the wound to open so that more permanent(nonabsorbable) sutures would be used to try to keep this from occurring. If it is less then 3-4 cm then it typically can be closed with an absorbable suture.