When looking for our dog we went around all of the dogs homes/rescue centres and there are so many older dogs that have been there awhile simply because they are getting on abit and people generally want younger dogs.
Also don't be put off by how the dog behaves in the kennel enviroment. Chances are it will be stressed and pretty unhappy

so ask to take the dog by itself with one of the centre's staff. This way you can assess what he or she is like on a one to one basis, how they walk on the lead, how they cope with traffic and strange situations etc. It is also a great way of finding out about breeds that you may be usure of.
As for looking for specific breeds, why not try a breed rescue centre or even consider a cross breed. There are so many crosses looking for a home and I'm sure your parents would provide a loving, caring home for any one of them!
Good luck