Number one in the international version is the Lloydhotel.
Amsterdam: Lloyd Hotel. Free WiFi. Worked so fast in this large hotel. So fast we downloaded an entire season of The Office on iTunes within two hours.
Even 2 years ago it was flipping fast and effect-less. Every 4 rooms shared a wireless point and there was more that enough through-out the rest of the hotel to get wireless outside, the lobby and beyond. I think the only place you don't get wireless is in the lifts. I also got upgraded to the D level penthouse on the weekend, so I'm a little bias generally towards a simply awesome hotel.
Since joining Backstage, I've spent a lot of time in hotels and always try to pick hotels with Free Wireless. Usually the problem I get is that the wireless is in the lobby not the rooms or its not actually free its pay wireless by someone like Tmobile, BT or much worst Eurospot. The other issue is that most hotels don't care or have no one who actually knows the difference. When trying to book a hotel in Newcastle I phoned up about 12 hotels and at one point had to describe the BT open zone, Tmobile logos over the phone because the reception couldn't tell the difference between free and pay wifi. No lie!
So yes the situation in the UK is pretty dire once you get out there. I'm certainly thinking about submitting some of the hotels I've been to on the international hotelchatter site. I remember a hotel I stayed in during my last trip to Manchester, it costs equivalent to 10p a minute for internet access through a wired connection (there were no bundles or offers available) I believe it was operated by swissport or europort. And thats the biggest problem, you can read the website and find it does have internet access but what kind is unknown by even the staff or management.
On the upside, GNER trains have wireless through-out the trains and although it costs about 10 pounds for 24hours, its certainly worth it for a 6 hour journey to Scotland. Recently I heard the Cloud have covered the City of London (business square mile) in rich wifi. I don't think its free but at 11.99 per month for unlimited (yes what does unlimited really mean) data its not a bad deal if your wanting wireless in the UK. The cloud has also been pretty good about inter-operating with BT and I think you can even interop with Tmobile hotspots. There's no douht where ever you go now in London at least, there is some kind of wireless and its usually operated by one of the big 3. Sometimes I do see Orange hotspots, but I can't seem to get Orange to just add it to my existing mobile bill.
Generally its all a big mess but soon I'm sure like the Marriot adverts I keep seeing, hotels will wise up and start highlighting the fact they have free wireless (although I'm sure it will just get added into the room bill).