I recently finished building up a mountain bike, with the help of a friend. My initial rides - a few miles, nothing too extensive yet - revealed that I need to move the handlebars a bit up and back towards the saddle to make my elbows happy; I prefer them to be bent more than they are now. I can think of two ways to do this: Raise the bars or bring them closer in, or a bit of both. (The stem is already at the top of the fork steerer tube, and I'd prefer not to get an extender on this bike.)
Background
The drivetrain is a Shimano mountain set I pulled off a hardtail 80's steel-frame mountain bike (upgraded in the noughties), hung on a hardtail 90's Specialized Stumpjumper frame (an aluminum frame with slightly more aggressive geometry). Neither bike had any suspension at all, including the front fork. (Due to my preferences. Suspension is nice, but I dislike the slight loss of feedback.)
I'd like to know what these changes are likely to do, and, possibly even more importantly, why this is the case.
Option 1: Get a smaller stem
This is an easy one, as the existing stem is quite long. Whatever I do, I'll want to bring the bars in. However, I could also look for a stem with a steeper angle while I'm at it. How will these changes affect how the bike handles? Will a shorter stem make the bike more twitchy, or less? (I quite like the way it feels right now.)
Option 2: Get some riser bars
This is a fairly simple way to get the bars closer to me. Rotating the bars one way or another will give me more options. However, I quite like the existing flat bar, as the simplicity of it is appealing from an aesthetic standpoint. Will riser bars affect the feel and handling of the bike?
Summary
I have two possibilities, and (I'm guessing) combining both approaches will likely be what I end up doing. Before I start ordering parts, which of these is likely to give me the correct reach while preserving the feel of the bike as it is now, and why? Are there options that I haven't thought of?