Both our Vizsla boys are neutered and it made not a bit of difference to their personality, level of activity, appetite etc. (It's also illegal in the ACT to own an entire dog without a special permit).
Not sure if things are different between the US and Australia but usual practice here is for dogs to go in to the vet hospital only for the day. Anaesthetic had no negative effects on either dog (one of our dogs was as bright as a button and jumping up and down when we picked him up from the vet surgery!) but of course different dogs react in different ways.