Im doing a MR to Tokyo Dec 9-11, and looking for a way to get good rates at the chains - *wood, Hyatt, Marriott. I tried Asiarooms, but they flaked on the rates. Is there any strategy recommended? E.g., wait till 5 days before to check again, etc.?

Im usually travelling there on business, so this is out of my own pocket and therefore, economy is an issue! I res'ed a room at the Century Hyatt for $186 a night - not bad, but hotel's a bit worn.

There have been several threads about finding nice rooms at reasonable rates, but the fact is that nicer hotels in Tokyo are expensive. For a MR, I would just go with an inexpensive, business hotel. For that, try:

http://www.japanhotel.net/

Some other threads for nicer-than-business hotels:

http://www.flyertalk.com/forum/showthread.php?t=597698

http://www.flyertalk.com/forum/showthread.php?t=587330

There are several others easily found with a search.

For the major international chains, I'd just use the hotel's website or try Priceline.

JR

Priceline can usually be played to get you into the Crowne Plaza in Ikebukuro for under $120/night. Small room but decently located to get to and from Narita -- I'd recommend taking the Keisei line from Narita airport to Nishi Nippori and switching to the Yamanote line to Ikebukuro. The hotel is right next to the station on the southwest side.

The only other international hotel chain that Priceline seems to regularly get is the IC Tokyo Bay, which is not very conveniently located for a short MR.

There is also a Hilton near Shinjuku but it will be considerably more expensive.

If you're looking to make your MR into a matress run too and want to do this on a budget, the only cheapo option I'm aware of is the Holiday Inn Tobu Narita.

It's not great, but the rooms are better (and bigger) than the standard rooms at Le Meridien Pacific (near Shinagawa station - which gets a big thumb down from me). Courtesy bus from the Holiday Inn to the airport is free and runs every 30 minutes or so, you can also get a bus from here into Narita Town.

Rates run from about 6,000yen per night per room.

I've done everything possible to maximise my hotel experience and comfort with my own limited 'own dime' resources in Tokyo over the past 4 years. It's very rare that inventory just 'opens up' a few days before your stay. The best bargains I've found have been booked well in advance.
(my favourite has been using Utell.com to get cheap rates at the Takanawa Prince)