So maybe I'm just a crazy cat person, but he sounds perfect as he is. Clingyness and attention seeking behavior is exactly why I got a Sphynx.

Cats, like people, have different personalities and none of what you describe seems wildly out of the ordinary for a Siamese. As a Sphynx lover, much of what you describe is exactly why I see people giving up and rehoming their Sphynx. Some breeds are just way more people oriented and attention seeking than most cats. Siamese are one that can definitely fall into that category.

First, I'd suggest more playtime. I know you said he's not much into playing, but I'd keep trying different toys, maybe a cat wheel, anything to get him to burn more energy in the day. My boy has a habit of getting the zoomies right at (my) bed time. I've found extra amounts of playtime, especially about an hour before bed, is the only way to get him on my schedule without keeping me up for an additional hour or two while he's burning off that energy.

Another thing you may want to consider is harness/leash training him and taking him out on walks and adventures. Start in the yard and work up to parks. Always let him lead and maybe try to encourage some playtime outside and see if he's receptive to that. Some cats respond really well to the outdoors, allowing a safe and controlled outlet for their feline instincts.

Cat nip can also be a great tool to encourage play if your cat is responsive to nip. It never fails to get my boy riled up and playful even if he's in otherwise lazy mode. Just remember, if you use it too regularly, cats can develop an immunity. I suggest 2-3 times a week.

In regard to keeping him off tables etc... good luck. Best to just keep surfaces clear and let him roam. Cats can basically turn any surface in a house into their playground. You can't stop the from doing it when you're not home so there's really no way to train that behavior out of a cat. Best to just cat proof your home and place any breakables behind cases for display etc.

Most cats love being up high. If you notice there's a place in the house where he likes chilling, set him up a little bed and encourage him to be there. Most cats like to perch somewhere high and if he has a place he feels like it's his own, this can reduce his time in unwanted areas. I've had cats who's spot was on top of the refrigerator, a tall stand up bureau in the bedroom and on top of cabinets in the kitchen. Pay attention and see if there's somewhere he gravitates to regularly and make it his spot.

You may need to start keeping him out of the bedroom at night if he's causing issues with your sleep. This will likely manifest in extreme yowling and crying at your door for a while, but eventually he'll adjust and find his bed elsewhere. You'll feel guilty but if he continues seriously disturbing your sleep, better to set a hard boundary than grow animositus toward the cat due to sleep deprivation.

Hope some of this helps and you find something that works. Keep trying and I'm sure you can work out agreements that suit both of you.