It would depend on a lot of things in my opinion. How far east do you want to go. Do you want to go to AA or AAA. I have watched a lot of baseball this year, and facility wise, the best are Farragut, CAK, and Catholic. If you go a little further east, Sevier County has a very nice indoor facility and their field is coming along.
You are never guaranteed to get along with coaches. Again, there are those who many say are the better coaches: Farr(CAK), Buckner(Farragut), Catholic's Coach. Further east there is Guinn(Pigeon Forge), Treywick(Sevier), and Jeff County's new coach seems to be good, even though he inherited a lot of talent.
There are tons of option, but all of the GOOD options have pretty good programs and who is to say that your son would be good enough and would be happy being a number 3 or 4 pitcher.
Lots to think about especially considering he is a Senior.
Good Luck!!!