Right on cue, here I am! I’ve had PsA for many years, but I was only diagnosed at age 60, when irreparable damage was found in my feet. (Don’t get me started …) Travel has been my favourite thing to do since I was twenty, and I’ve done a lot. In my fifties, I started experiencing fatigue (which took a lot of the fun out of the kind of travel that we were used to doing) and then since being diagnosed, I have been learning to travel with the limitations imposed by my inability to walk or stand for more than about ten minutes. Ten minutes is not long enough to get through an airport! About five years ago, I realized that it had come to the point of “get wheels or stay home”. Staying home was not an option, so with some reluctance, I got a mobility scooter. I was back on the road again, and being less vulnerable to pain and fatigue on my scooter, my able bodied husband and I could enjoy travel once more. We do need to adapt and take my limitations into consideration, but we still have plenty of destinations on our bucket list!
Oh yes, I’ll second everything tnt says about cruising. The beauty of a cruise is that you can do exactly what you are feeling up to that day. I’m not sure that a land-based tour (especially one of the kind that moves from this hotel to that day after day) is something that would be any fun to do in the shape that I’m in. Cruise travel is highly competitive and there are some truly wonderful itineraries out there. Our most recent cruise was a Panama Canal cruise, and it was without a doubt one of the most amazing and interesting trips we have ever done.
Since getting my first mobility scooter almost five years ago, I’ve travelled in Canada, the US, and also in Europe. With a little advance planning and creative problem solving, almost any destination is a possibility. Climb a mountain? No, but I wasn’t much into mountain climbing before my diagnosis either. 
Generally, I find accessible travel in the UK to be amazing, and far easier than travel in North America. European countries are variable in services and accommodations. Then there are the places I’ve been where you have to be very motivated and be a determined problem solver to have a positive experience. (Cuba is the place that stands out in my memory.) But it can be done.
How mobile are you, Toriop? (Love your screen name, by the way.) How far or long are you able to walk? Can you carry your own luggage? What kinds of activities are especially difficult or tiring for you? What kinds of places are attractive to you? What are your interests? With a bit of advance planning, yes, you can do it!