Even though I've polished all contact points and running Grayguns 17lb hammer spring and sear spring, the trigger isn't quite where I want it.
Should I buy the Grayguns ELS trigger/bar or spend another $66 for the action cleanup? Or...?

The Grayguns ELS trigger along with their polished and NP3'd sear and safety lever make a nice action.

You might look at a Superstrut from Robert Burke (The Sig Armorer).

I have two of the older versions and the ELS.

My 226 Legion has the ELS/SOT set, Gray Guns strut with a 19# spring and an Armory Craft hammer.

M11-A1 has the ELS/SOT, SA Superstrut with the supplied 20# spring and AC hammer.

229 Select has the new ELS, Superstrut with a 20# spring and AC hammer.

All have zero creep with a smooth 6.5# DA and around 3.5 SA.

The M11-A1 has the best trigger of the 3.

I am not sure what parts you have in your pistol but I had a MK25 that I installed Sig E2 parts in- newer strut and seat, and it made a big difference in the trigger pull weight and made it very smooth. I didn't have to replace the original spring but the pull was much better after the 2 parts were installed.

I was at the same point with a P6 (only I do #19 mainsprings.)

There aren’t P6/225 trigger or ELS options but the Sig OEM SRT kit made a huge difference! Of course in reset but it also smoothed the trigger pull.

I’d do the Grayguns SRT kit when it’s back in stock and strongly consider the ELS.

I wouldn't hesitate to put parts from Bruce or send a gun to him.

I have an older P226 nonrail he did some work on and couldn't be happier.

Years ago I was at Sigarms before they became Sig Sauer here in the states for a class with Bruce. The first day he checks everyone's gun. Played with mine and said the locking lug(could have the wording wrong) was loose and to remind him the next morning and he would look at it. The next morning at the Sig Arms Range I remind him. He looks at my P226 gets a vice and file and works on the barrel locking lug until he was satified. Huge respect for Bruce and Gray Guns. He didn't have to do that but did.

I sent that gun back with him to really work his magic with the trigger. That trigger is still one of the best I have ever shot.