Destinations for people who can't do a lot of walking

Rhein river cruise? (or perhaps any cruise) Rent a cabin in Muerren where you can sit on the deck all day and marvel at the mountain views? Casino at Baden-Baden?
Vienna: Smokers paradise. Excellent public transit (really excellent and extensive), also has a Casino.

You may find after some research that Malta would fit your requirements. It does have a casino and the bus network is pretty extensive so you get around easily. There are beach resorts or city hotels. You could even take a day trip to Sicily to see Mt. Etna on an organized coach tour. Not much walking involved for the mobility-impaired.

Seems to me a river or Mediterranean cruise might be something to consider. Just spoke with an older couple last week who travel and do a lot of cruising but can't walk very much due to age/health. They just booked a Mediterranean cruise on Norwegian...starts in Barcelona and ends in Venice, but there are tons of different itineraries. I understand there is assistance for folks that are mobility impaired. Maybe do a little research on the web.

The cruise suggestion is great. After going to destinations like Munich, Berlin, Paris, Strasbourg, and Nuremberg with two different groups of people who have difficulty walking, I would say that doing a European city-based trip is difficult. While public transit is great in most or all of these cities, seeing the city center itself is still going to involve a good deal of walking and often stuff like stairs. You might want to consider a location that is better seen by car, such as Normandy/Brittany or Provence, or renting a car and seeing the Romantic Road in Germany (where the towns are much smaller and you can park closer to the town center). As far as smoking and trains goes, most stops do not give you enough time to have a cigarette, but on a lot of trips you will be switching trains in which case you would then usually have enough time for one. Smoking regulations in train stations vary by country. In Germany there are smoking allowed areas on platforms, though. I have found that Europeans in general don't seem to get too worked up by illicit smoking on platforms, though. They're all usually doing it too.

Need a place where he can smoke and gamble to his heart's content? Look up the term "Spielothek". These shady little gambling parlors are EVERYWHERE in Germany and they never seem to close. But something tells me this is not what you're traveling to Europe to experience...

Casino gambling in fine establishments can be found in Bad Homburg and in Wiesbaden. Beautiful, luxurious casinos. He will need a suit jacket and tie to get in the door. Trams and buses may be good in the big cities, perhaps some ho-ho buses for sightseeing? Or have you thought of a river cruise?

Casinos appear to be pretty common in Europe. They are just more low key than the ones in Las Vegas. I have seen casinos in Lucerne and in Venice. The former was in a grand looking building on the waterfront, but the latter was more hidden away. I am told that there are a number in London, though I have never seen them. I don't normally seek them out myself, so I think you will need to do a bit of research, because as I said, they are mostly low key places.

Shame you ruled out Monaco. Excellent bus services, really cheap, both in Monaco and nearby France, excellent train services to nearby France, elevators and escalators get you up and down the frequent hills - free - and a halfway decent casino. The aquarium has lots of seats, so do the many gardens. There are a lot of elderly and mobility restricted folk and the town is made to accommodate them. Hotels don't have to be off the scale either.

i can't speak for elsewhere, but someone who is a serious gambler is likely to be disappointed in germany. the slots are video slots, even the 'classy' places that require jacket and tie are generally pretty lame compared to say, vegas-style gambling, at least according to my husband who grew up in vegas and my brother who is a gambler. i know nothing about these things but even the classier joints were still disappointing to them in the quality of gaming and atmosphere to them. an exception in germany may be baden-baden. the casino seemed really cool, but i didn't spend any time there aside from parking and using a restroom. monaco would be the answer, really. but if he's into serious gaming you are better off in vegas to be honest.

Thank you for the suggestions. I looked into some of these and I think Germany on one trip would be great with Baden Baden (I think he'd enjoy the spa as well as the casino), Rheine river criuise, Romantic Road bus. I guess Neuschwanstein is out of the question? I read you must walk to get to it? Will look into Vienna too if we have time. Will plan on Monaco also on another trip - planning to go abroad once this summer and again for Honeymoon in late fall or early winter ( hoping temps in Monaco not too cold then given the location). I'm thinking a city that has one of those double decker buses you can get on and off at all the hot spots may be good for us too. I will keep checking this thread for more ideas, thanks everyone!

If mobility is a serious issue, I would second Jo's recommendation for either Wiesbaden or Bad Homburg over Baden-Baden. Both are much easier to reach from Frankfurt International Airport (where I assume you will enter the country), and both, if you ask me, are far more interesting towns. And you are correct, Neuschwanstein is not practical if you can't walk up several flights of stairs.

Have a look at the Wiesbaden casino. Though I haven't been inside personally, I have to say it looks rather on the elegant side. Both Wiesbaden and Bad Homburg had their casinos before Baden-Baden. http://www.google.de/search?q=casino+wiesbaden&hl=de&rlz=1C1GGGE_enDE352&prmd=imvns&source=lnms&tbm=isch&ei=qzY0T4iNMM_EsgbglK3iDA&sa=X&oi=mode_link&ct=mode&cd=2&ved=0CCUQ_AUoAQ&biw=1619&bih=934