My standard room with a king-size bed, overlooking Suriwong Road
The De Arni hotel on Surawong (also spelled Surawongse, Suriwong and Suriwongse) Road ran a "soft opening" for quite a few months a few years ago, and they did need the time to work out the kinks in the operation. Since then it's become a nice place to stay and usually garners good comments on forums and travel sites. I've stayed there during both periods, myself.
The shower/tub combination and the refrigerator/coffee area
The hotel was recommended to me late in 2008 by a farang friend as a new place to try, and it was a pleasant stay at decent rates when I was there a few months later; there were deals to be had for 1,000 baht (about $29USD) at the time. As of today their web site lists rates around twice that much for the same room, but it's still a decent value, even without breakfast.
It's located next to the Le Meridian hotel, on the opposite side of the street from the Siam Heritage, close to the Patpong night market area, a lot of interesting restaurants, Soi Yipun and the nightlife along Soi Duangthawee (Soi Twilight). And speaking of nightlife, for those of you who are wondering there was a sign saying they had a 600 baht joiner fee that was pointed out by the receptionist before I could even say "hello" the first time, but I didn't notice it on the counter or anywhere else the second visit. Just FYI.
Also during that "soft opening" visit a friend came to drive me out a ways for dinner directly from work - dressed like the receptionist below - and when I came down to collect him to take him up to my room while I finished getting ready they stopped him and asked me for the fee. I was ready to say that I didn't know too many gogo boys driving new BMWs, but then realized I did know one; and by that time my friend had said something quietly to them himself that caused them to fall all over each other behind the counter, apologizing. HA!
The rooms come with the standard amenities: an electronic room safe, slippers, robes, LAN internet connectivity (wireless in the lobby), coffee and tea and a hot water pot, daily water, a small refrigerator and good air conditioning. I have a friend who loves to "play water," as he refers to it, so an actual tub is something I look for when I know he'll be passing through. I'm not sure if the smaller single rooms have a tub, so I'd ask. Those rooms are a bit small, though - I saw one.
As you can see in the photo above left the desk lacked a chair with a back to it and the sitting chair from in front of the window was a tad low for me, but that's a small thing for most of you who wouldn't be doing much at the desk, anyway.
For those of you who look for a pool, don't bother - there isn't one. The gym room isn't very large, but the equipment they've stocked it with is decent and it's kept clean. The morning buffet in the restaurant had food for the Japanese clientele in addition to the standard fare - but the omelets were good. One morning I was amused to see one of the restaurant staff running around in his socks, as though someone had taken his shoes or slippers, but I didn't ask why he only had socks on his feet. From the looks of them he'd been wearing them for a while. I haven't had lunch or dinner there, and frankly there are far more interesting-looking places outside of the hotel, anyway.
The staff - such as the receptionist above - have always been pleasant and efficient. During my stay while they were all still somewhat in training I returned one afternoon to discover that housekeeping left a trail of very dirty rubber slipper footprints across the room and back, but they were quick to send someone up with a mop to take care of that.
The rates through their site today were much the same as Agoda quoted, and I'm guessing they now allow others to book them, too. They're worth checking out.