A '90s mountain bike is quite versatile in that it can accept many kinds of components, thus you can upgrade slowly over time, or go all new (or new to the bike) parts. Modern tires and components really give one a lot of choice when it comes to updating things.

Show Us Your Vintage Mountain Bikes is a great thread to start with (309 pages!), with people posting stock/original examples as well as ones modified/updated.

Show Your Vintage MTB Drop Bar Conversions thread is a fun one for me (as a road bike guy who is way too tall for pretty much all vintage mountain bikes, sadly) as you can see people getting away from traditional outfitting of such.

People put swept back bars to make a sort of townie/urban bike as well. Like you, I often start with just a frame to build up, now that I know what works well for me and what kind of look I am going for. It, of course, wasn't always like that. I started with no knowledge and slowly acquired it.

Keep telling us some plans you'd like to explore for the bike to get your post count up and to give us a better idea of things. There are many here that can and want to help!