Lots of good suggestions above but some of them can wait a little while. The Honda 3.5 is a great engine but does need some preventive maintenance along the way. FWIW the Valvoline Restore and Protect is probably the easiest way to clean things up.
Around your age/mileage you should replace the timing belt, tensioner, idlers, water pump, thermostat, and during this job the spark plugs and drive belt (and probably the drive belt tensioner given thatvit will have to come off anyway). OE parts are best but the Aisin TKH002 kit from rockauto is arguably just as good (do not buy the counterfeit parts from amazon or ebay). OE for the drive belt, INA is fine for the tensioner. Only OE, NGK, or Denso high ignitability plugs unless you want to replace them again in the near future; the good ones are spendy but worth it. And never buy them from Amazon or ebay.
The valve cover is not entirely surprising if this car has the original PCV valve (located on the edge of the cover to the right of the oil fill). Use the OE part here and replace it about every 40-50k miles. I would not remove the valve cover yet; the entire intake needs to come off to access them so you can wait till the valve adjustment. Most times the valves don't really need any tweaking until around 150k. At 155k two of mine were a few 1000ths out but the rest were fine.
Also it's a good idea to flush the brake fluid every 3 years as stated in the manual. And power steering fluid isbprobably less than ideal at this point. Lucas PS fluid with conditioners is great for the Honda systems!
ATF should be replaced at least every 30k miles. A single drain/fill is usually enough but more may be needed if it has been neglected. See the model-specific forums for the preferred juice; many on the Honda Odyssey forum prefer DW-1 or Maxlife. I have used various major brand ATFs as long as they specifically say compatible with DW-1, and they all worked well.
As I mentioned, see the model-specific forums for additional issues to resolve.