I used to do many TR visas in Saigon and I thought it was possibly the best place to get it done. Of course Vientiane used to be the surest place to avoid issues. Also enjoyed the experience in Hanoi, so plenty of options close by.
Would be interesting to know how things have changed since countries opened up. Is it still a simple and hassle free process in Saigon? I'm thinking of either Saigon or Penang for a TR visa trip in early Dec.