Yeah, you generally want as large a tire as you can fit. A Cypress can possibly handle up to 42mm or 45mm wide. Your closest clearance will probably be in the rear, at the seatstay or the chainstay. See if you think your frame can take an extra 5-10mm there. Remember that both the tire width and diameter will grow with larger tires, so measure accordingly. Height probably won't be a problem, except for possibly at the chainstay -- you may have a kickstand plate or a fender mount down there that may limit the tire's diameter. Your front tire should have plenty of clearance for whatever size you want.
Two related questions:
- Do you have fenders or mudguards? These can limit tire clearance.
- Does your Cypress have disc brakes? If so, you could go to the extreme and change your wheels to 27.5" wheels and run perhaps a 27.5x2" tire. That would be a wee bit smaller than your current overall tire diameter (684mm vs. your current 698mm), and it would offer a significantly softer ride, given the right tire choice.