There are about a bazillion places to go in the Sierra Nevada, and most of them are beautiful. It sounds like you don't have anyplace in mind. The problem is that so many trails have trail quotas in order to avoid overuse. The trail quotas can be dealt with in advance by way of a wilderness permit reservation which costs a few bucks. Then some portion of the quota is held until the day before the permit date, and these are for "walk-up" permits, which generally are free (although there may be exceptions). Then there are many trails which have no quotas, but you still have to get a free wilderness permit. So, which way you go kind of depends on when and where. Some areas will allow you to take your dog along, and some won't. Some people go to fish, and then some people go to actually catch fish. Some backpackers will tolerate having a few strangers on the same trail, and some need to be out in some really deserted spot. If the fishing is that good, then there will be fishermen up and down both banks and wading in the middle. Some places will require that you store your food overnight in a bear canister. Other places don't care.