well if you are at 150k or so, i say you check these out and do them. of course if you already did, don't do so again...
-Coolant Flush
-Oil Change
-Tranny fluid change
-Air filter
-Air cabin filter
-Spark Plugs
-Lube hinges and latches
-Inspect brake hoses
-Bleed brakefluid and replace with new Heavy Duty Dot3
-Inspect all fluid levels (Brake, Clutch, Power Steering, Coolant Level)
-Check suspension bolts and tighten as necessary
-Inspect autotensioner and replace as necessary
-Inspect serpentine belt and replace as necessary
-Inspect CV joint boots and replace if cracked or worn
-Replace front and rear brake pads
-Silicon spray all door and trunk seals
-Inspect lightbulbs
-Valve adjustment
-Rotate and balance tires
-Recharge R134a refrigerant if your A/C is not blowing as cold as it used to be
-Adjust Parking Brake (if not fully engaged within 7-9 clicks)
-Replace Battery (it may be nearing the end of its useful life)
-Inspect and adjust idle RPM
-Replace water pump
-Replace starter (if you get that scratchy sound on cold startups)
-Replace Oxygen Sensor (even if its not giving you a check engine light, replacing it at your mileage will almost certainly give you better fuel economy)
did i mention motor mounts in there somewhere? i would take a look at them too to see if any needs replacing. also trunk and sunroof for leaks, i know the older rsx have troubles with the seal being bad or need changing.