Well for half an hour's drive into Leeds, Horsforth would be a good area, also has train links that are a 10min ride. Is a good area and has decent schools I think (haven't got kids though so don't know for sure).
Anywhere in North Leeds is usualy fairly good (bear in mind, I'm biased cos I'm from North Leeds - Cookridge/Holt Park to be exact). I would recommend Cookridge/Holt Park - (next to Horsforth) as it also has good transport links and is close enough to communte each day (20/30mins).
As said above, Farsley and surrounding areas (Pudsey, Stanningley, etc.) are pretty decent as well. Otley & Pool-in-Wharfedale are also lovely but a little further out. Roundhay has some nice areas in it and a great big park (where Robbie WIlliams did his recent concert) that the kids would love.
Avoid Beeston, Gipton, Chapeltown, Harehills, Middleton, East End Park.... um that's all I can think of for now.