Other than the shocks wearing out, has anyone upgraded suspension wear items (shock mounts, bushings, etc) as the miles add up (eg, after about 30-40K miles)?

I know that on the BMW 3-series, for example, that there wear items that sometimes need replacing (ball joints, trailing arm bushings), but I am not sure on the RX-8.

 

Well I would imagine there will be replacement items. Shocks probably #1 on the list. Rubber bushings next.

If the Miata's are any indication you will have the car for a long time before things need replacement.

 

60,000 miles and the only thing I had to do was put grease fitting on my sway bar bushings.

https://www.rx8club.com/series-i-trouble-shooting-95/something-owners-aftermarket-swaybars-might-want-lookout-65304/

 

Parts on modern cars last a long time, my saturn has 243,000 miles on it and the suspension parts still work fine.

I had a thunderbird that had worn out suspension joints, but then again that's a Ford from their crappiest days, that car's engine was also prone to head gasket failures and the plastic trim tended to crack in the sun (huge cracks)

I wouldn't worry about it and I second expo's suggestion, put zerk fittings on the joints to grease them every once in a while.