Front loading washers are easier on dogi than top loading machines, and can handle heavier-weight loads better.
Many laudromats have both types, so use the front loader if you go that route. Then, next time you're in the market for a new machine, get a front loader; they also use less water, less detergent, are quieter, etc.
If you don't want to go to the laudromat, use gentle cycle on your machine, and slow (or no) spin cycle. You'll have a very wet dogi, but it won't get as beat up. Then hang the dogi on a pole to dry rather than putting the water-logged beast in a clothes dryer. (If you live in a humid clime, you can start the drying on a pole, then finish in the dryer.)
HTH.
Yours in Budo,
---Brian---