Where do the tubes go?

Studio 1,
You raise some good points for the OP as far as distinguishing in general pentode vs triode tube amplifier options. I like many who ventured from SS amplifiers to tube amps went the route of pentode initially, (triodes came later). These are predominantly push pull and often class AB configuration. This genre offers much flexibility in price, power and many brands and models and can provide very good sound quality when executed well.

Triode specifically directly heated triode (DHT) is another niche, examples are 300b, 2A3, 45, 211, 845 etc. These are used often as SET(class A by default) but also class A push pull. These amplifiers will as a rule have lower power output but offer a different sonic presentation that some will find very natural and life like. Both categories of tube amps have their admirers. Speaker selection is a critical aspect when considering a given amplifier.

Aceofhearts, I'd recommend that you do some reading on DHT and pentode tubes and certainly listening to these different types of tube amplifiers to help determine which type will please you the most.
Charles,

No stereo component functions alone, or at its best with just any others, so always best to consider the key component inter dependencies, especially when dealing with SS versus tube based gear.

Assuming you have a good system already, and are looking to add another built around tubes, I would set a budget for the new system that is built around tube amplification of some sort and go from there.

How that might best play out would then be determined by what your goals are for the system sound wise. Room size, types of music listened to, volume to be listened at, all the usual factors should be considered up front.

If you are just looking to add some tubes into an existing system, a tube source like tube DAC is the most practical place to start. Tube rolling in a tube DAC will provide opportunity to experiment easily with different tubes to tweak the sound and learn initially.

What speakers do you have currently? That would be a big factor in determining whether a change to a tube amp or integrated is a good investment alone.

A tube pre-amp is another option, but I would consider input impedance specs of whatever power amp was to be used with it first before doing that, and only if a analog pre-amp is needed, ie in case of both digital and analog (like phono) inputs. 30Kohm power amp input impedance or higher is probably a safe bet for good performance with most tube pre-amps.

No right or wrong way to start. Just some more likely to work out better sooner rather than later if you always consider the big picture before making a move.

Aceofhearts what does your system look like now and are you going to replace your speakers?