hero had been on a little heater an hour ago and now has the big stack of 955. (flopped set and nfd/turn flush to stack two vs for around 75bbs each.) have half my chips in a rack as I'm planning to leave in a few hands.
most stacks are 200-400 with a cpl of shorties. v is a loose passive player in hj with 155.
v2 is a somewhat aggro player in co with 250.
hero is utg.

hero limps with 5d7d (not part of my usual utg range but was feeling like gamboling a little)
mp calls
v(hj) calls
co raises to 11
SB calls 11
bb calls 11
hero calls (get close to 4:1 often 6:1 as both mp and v should be calling)
mp and v(hj) call

flop(66)
Td 8c 4d
SB checks
bb checks
hero checks (planning to c/r with 12 out draw under right circumstances)
v(hj) bets 15 (Tx,8x, flush draw, under pairs, over cards, sets)
co calls 15 (good Ts maybe 99, flush draws. co is a somewhat aggressive player so I assume hes raise with nfd+2 over draw)
folds to hero
hero raises to 100 (puts in roughly psb putting both Vs to a commitment decision.)
is this a good spot for the semi bluff?

I think the raise is too large. You can accomplish the same thing with a 75 dollar raise. Either way when you raise to 100 the NFD can still call.

a) We're nowhere near deep enough to call raises with a suited gapper from out of position. The PFR only has $150? He probably needs $350-400 at least for you to call pre-flop. If the entire table is at around 2-400, you probably shouldn't be calling -any- raises with SCs. Fine to open them from later position, of course. And you can sometimes three-bet from the blinds with them depending on your image and table dynamics. But playing them just to hit your hand from OOP is just burning money.

b) Secondly, we're out of position, and playing suited gappers OOP is really really hard: When you flop good with these hands, you're flopping draws, and it's so much harder to manipulate the pot in your favor (small when we're still drawing, big when we hit and get paid off) from up front. I say only half jokingly that any losing player could probably get to at least break even if they just always folded SCs and gappers to raises when OOP.

c) If you do find yourself in this position, obviously you want to take the line that gives you the most fold equity. And I think most players at these stakes don't play their draws aggressively enough. So in that respect, raising big here isn't a bad idea, at least in concept. Problem is - do you have fold equity? V only has a bit more than your raise size behind, you look like you're drawing, he raised pre-flop then c-bet into multiple people, so you'd expect him to have some sort of hand. I think you're getting called here a ton.

d) The CO called with the table still behind him to act (yes, everyone checked, but 'checking to the PFR' is so standard we're basically in the dark). So there's a small but non-zero chance CO is on a better draw (higher flushes, 79 (which means your gutshot 6 isn't an out).

Once you're stuck in this position, I'm calling the flop c-bet and evaluating the action. If I hit my gutshot or flush I'm betting for value but be prepared to fold if you get heavy heat, 'cause I don't think our five-high flush would be good.

I'll repeat the main lesson: Don't play suited connectors & gappers from OOP from late-position raises unless you're waay waay deeper.

Fold pre UTG at a full table. At a passive table I'll raise this UTG if short handed. As played the raise is fine if you are shoving any turn card or calling off a flop shove.

limp calling with 57s utg is lolbad. Raise or fold

Winner's tilt.

Relative stack sizes.

Fold pre.