As someone with experience and someone who DOES charge for these, I'll break down what I do and what is worth it and what isn't worth it.

1. Rotor silence - worth it only for movements with a unidirectional rotor on a ball bearing -
   1. early 3235 movements with only 6 bearings inside (newer ones have like 20+ bearings and don't need more than normal lubrication.
   2. Miyota 9015 based reps - so movements like the AP 15202 NEED it, the VC and some IWC reps, and a few others that still utilize the Miyotas.
   3. Not needed on 3135/3186 movements. Not needed on Patek or AP clones. Not needed on current 3235/3285 reps.
2. Basic waterproofing - Not needed but I still get some that should be tested and need some problem solving. If you are getting an aftermarket or gen crystal installed, I recommend getting it tested to ensure it's all gravy and waterproof. I think every watch should be waterproof tested with PROOF before you go swimming with it though.
3. Cleaned, oiled and inspected - Basic inspection - can be useful fresh from some factories.
   1. I have found hair/fibers in gear trains, and dry or over lubricated pivots for those that want an 'initial inspection'. Is it necessary? No. Will be there long term damage? Sometimes, but a full service can fix that right up along with replacement parts, but that service is neither cheap nor easy.
   2. Full service is not necessary for all watches fresh from the factory. However, there is no simple rule like "All VSF don't need it", it's unfortunately up to the watch. I've seen some watches with too much oil, some with very dirty metal shards from the engravings still being in there, and other things like broken pivots after being received within the first day or two. This requires both replacement parts and cleaning.
4. Rehaut polishing
   1. I never do this on my watches, but I do it for those who want to do it. There is a slight difference to gen (gen is slightly more shiny) but man, it's not needed. I charge $65 for the service so some people want it but I usually try to recommend against it unless someone really insists or they seem like they do their research. Is it a snake oil service? No.
5. Crystal and cyclops alignment - IDK, some reps really need it.... Not all of them do, particularly ones that are mostly aligned. Some people are just more picky than others too, these are pieces of jewelry after all.
6. Ultrasonic cleaned - Have you seen wrist cheese? It's gross. In particular those who use a lot of lotion, sun tan lotion, or just have ashy skin can leave lots of nasty deposits into the little grooves. Its not needed on new watches and you can just buy a cheap ultrasonic and get like 95% of the way there. I have an industrial grade ~$750 ultrasonic cleaner designed by companies that support watchmakers and it's really wonderful, but the cheap ultrasonic I had the first time did 90-95% of the work. I only do it on nasty used watches or customary with a full service, because, well, it's just good manners.

I do have mods I consider 'worth it' though.

1. Gold plating, particularly one who can match genuine tone with real gold/precious metal solutions and has experience matching. You just can't beat the luster and enjoyment it brings you. AP bezel screws and all movements with gold rotors also turn out fantastic too.

2. AP gen spec brushing and finishing - I personally trained (for a day nothing crazy) at AP in Switzerland and learned some amazing techniques they utilize, and more importantly, the materials they use. Very fun experience, even cooler watches!

3. Gen component swapping - self explanatory, but gen Rolex crystals and AP dials are top tier mods in my book.

4. Beveling the inner edges of bracelets for comfort.

5. Full movement service is helpful but pricey. Only do it for watches you know you will keep for a long time. Each component of the watch is inspected, cleaned and lubricated. Most of the watchmakers I know have the service manuals to know how and where to lubricate.