I hadn't seen the wheelchair ones, but my wife and I always try and do a Segway tour when we are on holiday. You can get as close to sights as walking, but cover much more distance. Especially helpful in places like Lisbon, where the hills are 'significant'! Once you get get over the first 10 seconds of your brain telling you you are going to fall over(!), its dead easy! Try one next time you're on your hols. Unfortunately, they can't be used for tours in UK cities, as they count as an electric vehicle and need to be taxed, have lights etc, so its not practical, but most 'foreign' cities have them.