First off---painting oak is silly---unless all the grain is filled. Reason---it simply looks like painted oak---which you have found unacceptable. Second, to stain, the wood has to be bare--NO finish. Removing finish from trim is more time consuming and expensive than finishing/replacing it. IMHO, painting oak trim does devalue the property. Which Zinsser primer did you use? Bull'seye or BIN? BIN is the better choice for trim. White trim is traditional and can also be modern. Buying paint grade(the least expensive type trim anyway) pine trim, priming with BIN, and adding two coats of the paint(usually gloss) is the minimum process. Poplar trim can be painted more easily than pine. Stain grade trim is more expensive(pine wood is difficult to stain evenly). Minimum process for stain grade pine is a wash coat(preconditioner), stain application(preferrable wipe on/off since that allows much better color control), light hand sanding, and several coats of varnish. Installing trim can be a good DIY project. The list of necessary tools can be as simple as a hand saw/miter box combo(as low as $20), a smooth face hammer($10) , a box of #8 finish nails($4), and a book of installing trim($20). Or as complex as a power miter saw($200up), a compressor($100up), a finish nailer($80up) learning to cope cut joints(coping saw/hand rasps at $20up) and more. I have tools worth over $1,000 just to install molding and doors. And some other tools to make molding, if necessary. Base molding and door molding can be a one person job. Chair rail/crown molding requires two people(or several special tools)

@K paulson, I can't say for sure without seeing it a bit closer, but I'm about 95% sure that only your casing is oak. Those look like common pine windows. As far as painting, its not uncommon at all to paint them and is not subject to any major problem as such. Basically everything that you can see and touch when the window is closed can be painted without any issue, and actually a little farther into the jamb than that. The grids will be a pain (removable?), but other than that, pretty simple stuff. Just a lot of taping and prep work.

I mean, the rooms where the orange oak doesn't look so terrible are the ones where we chose cooler colors (with green/blue undertones). I think this is builder grade trim which is probably why I don't like it so much--it reminds me of my parents house with the same style trim but the poop-brown color. Let's say I was willing to try and preserve it, which I am willing to but it's gotta look good. How could I "refresh" it to make it look good again? It feels like it's so dated and much of it has NOT been taken care of super well. I really like dark, rich woods (think Java) and I've never been a fan of how bold oak grain is but I'm sort of hearing re-staining it is not really possible. My photos show just a little snapshot of it but I especially don't like how it looks when viewed as a whole. The only place it seems to actually look okay in is the bathroom (next to retro blue tiles) and the kitchen (with black counters and dark backsplash). I've been looking at proposed colors that might go well with the oak color--it's possible we just haven't found the right blend of color to make it look good to us. Ultimately it's up to us but I'm not opposed to saving money and not replacing it/painting over it. But I haven't yet seen an example of making it really work enough to make me say, "That's beautiful."

You can use most colors, with your stained trim, except yellow shades,. Blues, greens, aquas, whites etc all go very well, with stained trim.