65 out

If you have 65 left with two darts, you can go for T15 - D10 and a single 15 will still leave you a double bullseye with your last dart.

But what if you have 65 left with 3 darts to throw?

• Single bull + D20?  If you miss the bullseye, you'll have two darts to clean it up.  Chances are you will be under 60 and will have a two-dart out.
• T19 + D8?  A single 19 leaves you 46 which becomes 40 or 36 by throwing your second dart at the 6/10 wire.
• T15 + D10?  A single 15 leaves you 50 which can be 18 + 32, if you don't feel like going at the double bull with your second dart.

I took the third option Saturday night.  After I threw my second dart at the single 18, I heard my opponent (a very good player) laugh and say "smart dart".

Looking at this now, I think the second option might have been a better choice because the set-up dart if you miss the first triple is easier.

All of these are pretty similar, so it may just depend on how confident you are feeling with your single bull or your triples.