Europe - One-day trip from London... CPH, BRU, or LUX?

Hi, I have some free time in London at the end of an upcoming trip there in June. My free time is from Friday mid-day to Saturday night. I have a $300 BA voucher I need to use by the end of June and I checked flight prices to nearby cities and it seems like only CPH, BRU, or LUX have reasonable fares (~$400). I was wondering if anybody has suggestions on which of those cities would be best to visit for 24-36 hours. My preference is Luxembourg since it seems like somewhere that I probably wouldn't make it back to again on another Euro trip, but I wonder if 24 hours is enough time to see stuff there since it sounds like Luxembourg City isn't that big and some of the main attractions are outside the city (not 100% sure if this is the case). Brussels sounds nice and so does Copenhagen, but I have no idea if 24 hours is a good amount of time to see the main attractions in the city. Any suggestions or trips would be greatly appreciated. Thanks!

For Copenhagen a day and a bit is really too short.

I've never really warmed to Brussels for some reason - but that's probably subjective (there are other towns in Belgium that I really like). However, regardless of any personal preference flying to Brussels is a waste of time and money (or a voucher in your case) because it's so much easier and quicker to go there by train

Luxembourg Ville is a very pleasant little town, and probably just about the right size for the short trip that you are planning. There is some lovely scenery elsewhere in the grand duchy, and you won't have time to see that in a day, but that shouldn't stop you from visiting the town.

Thanks!!! Luxembourg it is! Although I despise the hop-on, hop-off tours, I will probably end up using it there in order to maximize my limited time. Hopefully they have a hop-on hop-off bus.

Good choice :D

Bus in front of terminal will take you downtown. Make sure you stay downtown and not in Kirchberg (EU and Financial centre).

Take the Casemates tour, the electric train tour or the double-decker bus tour if you get a chance.

Place d'Armes is where you want to go for early evening entertainment. Later, migrate to the old town around the palace or Rue de Hollerich which is near the station. The other streets near the station offer slightly more, uh, late night entertainment of doubtful quality.

PM me the dates and I can give you a more specific list of to-do's.

Thanks everybody for the tips! I am booked to go to Luxembourg next weekend. I'm trying to find hotels and realizing that hotels are quite expensive! Any suggestions on how to get a cheap hotel (up to $75)? I tried using SPG, Marriott, IHG points but no hotels located in Lux. Priceline doesn't have name your own price for Lux. Hotwire has a 4-star room for $85. I was wondering if anybody knows of any better deals.

Thanks!

Greetings, I came upon this as I was looking for ideas for Lux. We are flying in on a Saturday in Oct and probably staying 2 days before heading into Belgium. Ideally we'd like to do the city and a trip (day?) to a winery in the Moselle. Itinerary ideas?