When to go solid state vs. vacuum?

I suggest you go and listen to a bunch of speakers in your price range and a few above it and a good local dealership. Select the speakers and then select an amp to drive that particular speaker in your particular room and at the volume level that you prefer. You should be able to hear the differences between SS and tubes on a good pair of speakers. Once you have decided on the speakers and know what their requirements are, you may want to ask the question again. But that is how I would start the process. It should be fun so enjoy it.

Yes. Its dependant on your taste in music and of course your ear. I run tube but will be seeking out some ss gear that's more laid back because I'm major OCD and when a output tube goes I flip. Ill keep the tubes because I don't want to miss and regret selling them. There's some ss gear out now that doesn't present that hard edge. I'm holding out to see what the new Ayre AX-5 integrated sounds like and it could be awhile before its on the market.

Choose your speakers first, then what type of amplification best suits those (1)speakers and (3)upstream components, within your budget, in your room, at the volume levels you desire, with sound characteristics that are most important to you, best fit the accommodations you can provide, with the level of maintenance you are prepared to offer, and the level of value you expect to maintain.

Tubed preamp is no problem. easy to have and maintain.
Tube amps are harder to maintain.
Then tube costs.
lus tube fear. (buying tubes is crazy, way too many choices)
Anyway, for a 'never had tubes' person, i suggest only a tube preamp.

If you want to try a tube amp PrimaLuna is an easy way to go. They sell integrateds which have 4 preamp tubes and 4 power tubes, not too complex but it still allows for trying different tube combinations (known as tube rolling).

The power tubes are continuously autobiased. The biggest problem with tubes for the beginner is biasing power tubes. With a PrimaLuna, and some others, you don't have to do it, the integrated does it for you. This also keeps it sounding its best, reduces wear on tubes, allows you to use different types of power tubes (e.g. EL 34s or KT 88s) and makes matching power tubes less important.

PrimaLuna has received tons of awards and great reviews, just google them. They are built to last and are not expensive.

PrimaLuna is a great place to start with tubes. Once you become a little knowledgable about tubes you may want to try something more esoteric or expensive. That's my 2 cents.