I really don't know. Definitely not anything where I am hunched over the tank or the weight is on my wrists. Probably keep the scooter for commuting - anything bigger and I can't get through the gaps, plus the mpg is so good (95-100mpg) and a bigger bike may knock off all of 2 or 3 minutes in travel time. I usually catch them up in the filtering after the open roads, so can't see any benefit in that for my 15-mile commute.
Would really like a 400cc naked, shape of Yamaha SR although the reviews aren't that good for that. Like the old 80s look of road bikes, takes me back to my youth. Definitely don't need anything that is capable of gazillion miles per hour, just something that has a very reliable engine and mechanics (rather than technology), capable of going abroad so must be comfy for my fat arse and options for luggage.
Still looking. Probably end up with an old virago, lol.