I'm currently exploring the nebula NGC xxxx (forgot number, some 2500 ly west of sol). It has lots of class O stars (blue giants). Funny enough the description states that these stars rarely have ages > 10 million years, but most I found showed ages a lot higher than that (50-100 million years).
Speaking of weird: This whole nebula has given me a very strange feeling. Super giant blue stars, orbited by many other stars (instead of planets). And all of the time you have the red background of the nebula. Makes for a very eerie experience, tbh. I'll be glad if I leave this place and can explore "normal" systems again