Well, most of the design criteria were heavily influenced by cost and size, since I want to make about 50 of these. The relay will be switching up to 10A of 120v AC.
The js1-48V relay I am using costs $1.57 where a usable pcb 10A 120v ac coil relay is $4.56, and the dc relay with the 10uf cap seems quite happy with no chatter, etc. but there may be problems I'm not aware of. Heat and size are problems, so by replacing the relay, the heat sink required by triacs, etc were prohibitive.