My 99 has a feed dog cover I slide over the throat plate and it works well. There are various kinds, I have a screw-on cover too, it works just as well, it came with a buttonholer. 99s can't drop the feed dogs, but a few vintage straight stitchers can. All 201s have this feature, as well as the later style 15 (with the stitch length lever and reverse).
I took my 201 to heart and it has been my favorite machine since I bought it four years ago (I can't remember exactly). It was rather a chance buy, but I can recommend getting an old straight stitcher. I keep a freearm zigzagger too, it has lots of stitch patterns to choose from. If money is an issue keep an eye out on a local auction site or charity store, I'm sure something will turn up at the right price. Models like 99, 66, 15, 201 are very safe buys, all parts are easily found, replacement bobbins and needles are standard as well as feet and accessories (I buy mostly used ones I find on the web). If they look like they are in reasonable shape under layers of dust they will clean up nicely. Old machines from the 1920s and 30s almost always need rewiring if they haven't already been replace. It's rather expensive to have it done, 1950s models and younger tend to have better wiring.