UTG+1 is 30% and a showdown muppet. MP1 is 35% vp$p and 10% pf raise.

Party Poker No-Limit Hold'em, $0.5 BB (10 handed)

UTG+2 ($44.4)
MP1 ($46.15)
Hero ($88.25)
MP3 ($49.4)
CO ($22.03)
Button ($16)
SB ($25.75)
BB ($81.85)
UTG ($77.55)
UTG+1 ($39.5)

Preflop: Hero is MP2 with , .
1 fold, UTG+1 raises to $2, 1 fold, MP1 calls $2, Hero calls $2, 5 folds.

Flop: ($6.75) , , (3 players)
UTG+1 checks, MP1 bets $0.5, Hero raises to $5, UTG+1 calls $5, MP1 calls $4.50.

Turn: ($21.75) (3 players)
UTG+1 checks, MP1 checks, Hero ?????

That's not exactly the turn I wanted but I know I at least have outs. How do you approach this now and what do you do if check raised?

I think you have to check there. One of them most likely has the flush.

When you have 2 callers with a flush draw possible, usually one of them is on the flush draw. In this case, I can see a check-raise 50% of the time that they check. The problem is that since you have the set, you pretty much have to call the chk-raise to draw to a full house. I think that if you bet the alternatives are that you either don't win any extra money, or you are check-raised and stand to lose more money.

I suppose that is a good point. If you bet on that turn there is not much they can call you with except the spades. But what about two pair or lower set, you could get some extra cash off of those hands. And what about the concern about giving any spade a free card?

I would prefer to keep the pot small, and would call a pot sized bet on the river if no spade hits. This is about the same amount Hero bet out on the turn. You might even induce a bluff, if they think you are afraid of the flush and make some extra money that way.