Spot,
If you don't want fancy, try the Downtown-Capitol Hill Best Western. It's only about 5 or 6 blocks from Union Station, although you may still want to take a cab to reach it. One has to walk about 3 blocks out of the way, as there is no bridge over a highway between the hotel and the station.
I stayed at the hotel about 2 years ago. It was clean and decent, but certainly nothing fancy. When I checked tonight, I put in a date of May 21 for 1 night, and they returned rates in the $125-$130 for either AAA members or anyone over 55. Even if you don't qualify for either of the above discounts, it's only about another 10-15 bucks more.
There is a restaurant right in the hotel, so you don't need to venture out if you don't wish to. One word of caution, if you do go out at night, please take a cab. It's not a bad neighborhood right there, but a few blocks in the wrong direction and you could get into trouble. So spring for a cab if you do go out at night.
You can find their website by
clicking here.
If you want something a little more fancy, then look at the Jurys Washington Hotel. This is a very nice facility and I frequently stay here when I'm on business in DC. In fact I was there just last week for two nights. The hotel is located on Dupont Circle and is easily accessible by either a 5-10 minute (depending on traffic) cab ride or via the DC Metro's Red line. The Red line also serves Union Station, so you only need to ride the metro 5 stops with no need to transfer. The fare is $1.10 each way.
The Jurys Hotel is an Irish owned hotel. It's very clean they have nice large rooms, with a 25" TV, desk, free coffee, and high-speed Internet access if you have a laptop. There is an Irish pub for lighter fare and a full-fledged restaurant. Both serve very decent food, although the restaurant can be a little pricey depending on your point of view. Average dish costs between $18 - $25 bucks.
They gave me a price for the same night May 21 of $165, however I paid less than that on most occasions. Usually between $95 and $125 per night, however you will probably need to call them to get a better rate. They generally charge maximum via on-line booking. Their website is located
here.
With some more research you may be able to find other that are under $200, but these are two that I've personally stayed at and feel comfortable recomending. The Best Western is much closer to Union Station and cheaper. The Jurys is further away and a little more costly, but definitely nicer, newer, and more plush.