Belgium beer run with a side trip to London and/or Paris

They may be disappointed. Most smaller brewers, and practically all the larger ones, do not offer regular tours to the general public (too many sanitation adjustments required to justify the cost and small amount of foot traffic for most brewers). But many of them run an on-site cafe or restaurant. A smaller number will let your visit the brewery if you make prior arrangements. De Half Maan in Brugge is one of the few where you can just show up and visit the brewery, although increasingly more of this company's brewing is being moved to a modern facility outside of town. All of the Trappists breweries are strictly off limits to the public, except on some special occasions.

Personally, I find the best way to experience Belgian beer is simply to order it with your meal at a restaurant. Realistically, because of the usual high alcohol content, you can only sample one or two of the better beers per sitting without getting a little sloppy, so pacing yourself with food allows you to savor the beer a little longer.

There is enough art, culture, food and entertainment to satisfy most people even without additional side trips, take a look at the RS guide for Benelux. Distances in Belgium are short so you might not need a car (providing more opportunity for beer consumption). The non-beer drinkers could do chocolate runs/tastings (just as intoxicating). I returned from my first trip to Belgium last month and am planning the next chocolate run.

Yes, the chocolate is worth the trip alone. I am NOT a beer drinker (I never even thought I LIKED beer) until my first trip to Belgium last year. Man oh man, almost every single beer I had I LOVED. Find a bar with different brews and try them all. Some of them even drink like a fine wine. Even non-beer drinkers will probably fall in love with Belgian beer.

"Find a bar with different brews and try them all."

Then procede to the hospital for alcohol detoxification. Unless you go for the lighter lagers (Kristal, Stella Artois, Maas, Jupiler), you're looking at 7-11% ABV.

+1 on finding a beer bar. When I worked in Ghent, I found a place on the main square that had over 200 beers. When it came to the Tripels, two was my limit (and I'm 290 lbs!).

I'm also a homebrewer, and I second the thought about the breweries in Belgium--tours just don't happen...and I got that info from the owner of the best Belgian beer bar in Philly (Monk's). Even HE couldn't get in unless he begged.

You can visit Delirium in Melle near Ghent, or city brewery Gruut in Ghent. But you have to get in contact before to arrange the visit. Also the same for Het Anker (Gouden Carolus) in Mechelen and Duvel Moortgat in Breendonk, some 10km west of Mechelen offering beertours. Websites info also in English: www.delirium.be www.gruut.be www.hetanker.be and www.duvel.com

For an overview of links to breweries in Belgium: biersites.info It’s only in Dutch, but you can select English on many websites.
Over 200 beers in Ghent must be de "Dulle Griet" on the Vrijdagsmarkt. For a special experience order a "Max van het huis"! Also special in Ghent is 't Velootje.

"de "Dulle Griet" on the Vrijdagsmarkt"

That was the place...after a couple of days, the proprietor knew me by my first name. Loved his story about requiring students to give up one shoe whenever they ordered a Kwak. Highly recommended after having a great meal at one of the restaurants on the square.

Jturie – This kind of experiences makes a visit to a place so more special. I have visited many other pubs in Ghent, but have to admit till so far not the “Dulle Griet”. It’s for the shoe and the wide variety of beers that makes it such a well-known place and that’s actually the experience one will have when ordering a “Max van het Huis”. Have no idea if it will be a Kwak, their website doesn’t tell anything about it, but it’s worth a try.
Btw how is your opinion about Ghent, offer it enough for a longer stay?

About drinking strong beers, the advantage of city breweries is that you can walk "home". I don't want to patronize, but drinking and driving, be carefull or just don’t do it!
For going to Melle from Ghent one can take the tram to Melle Leeuw and the last leg to Melle Pontstraat (close to the brewery) with the bus.

There are also brewery visits available in London (Fuller's comes to mind) ...

There really is not much to do it Ghent for a tourist, but I enjoyed walking around the city, sitting on the square, and going into the shops. Met a lot of very nice people. I never went into the castle, and my two free weekends were spent in Brussels and Amsterdam.

There's the Ghent Altarpiece...

My wife and I have traveled many country's in Europe, tasting beers in each one, loving each one until we visited Belgium. Spectacular. It would be a crime for your husband and son not to visit Belgium / Bruges. Whoever your traveling with might not be enthralled with beer runs, visiting Bruges would be a treat for beer drinkers and non beer drinkers. The pleasure your husband and son would have would equal seeing youngsters at Disney for the first time. The term beer run in Belgium is an unjust comparison to an American beer run. Even beer in the UK is truly special.
Not sure why you are taking a train unless its cheaper. Brussels is a massive hub and flights throughout Europe. Enjoy your trip and cheers to your husband and son!