If you have the opportunity, go for it. I have a Saint Bernard myself, and I have to say that it is the best **** dog I have ever owned. Affectionate, loyal, dependable, playful (although also a bit mischievous at time) and extremely good with even very small children. I would recommend it to anyone - be good to a dog like that, and you get a LOT of dog in return.
Just don't expect them to fetch - some like it, but many (like mine) just give you that "I just GOT you your stick back. If you wanted it, why did you throw it away?" look. Oh and also drool. Amazing stuff, like translucent jello mixed with glue.