Against my better judgment, let me give a more sincere and thoughtful answer in regards to the San Juan.
I think wether it is worth it or not isn't a cookie cutter answer.
The first consideration is the distance. SJ is about MM 58. And unless you stay at the mouth, you will need to venture up 10 - 15 more miles to find a campsite. My experience in houseboats is that they usually cruise around 8 MPH. Slower if you are towing heavy boats. Maybe a bit faster if you are solo. But in the summer, we never just "go" to our spot. We stop and let people on/off the ski boats. We stop for a "fire drill" where people swim. Either of which will slow down your cruise speed. I think a more realistic cruise speed for the entire duration is likely 6 MPH. Maybe slower. So do the math from your marina to decide if you are willing to spend that much time on the boat.
With those distances come increased fuel consumption. My last houseboat had 160 gallons of fuel, and going to Cha took almost all of that. So you need to make sure your boat has the legs to do it (most of the newer boats this likely isn't a problem). Also need to make sure you have the fuel capacity for whatever other boats you take with you, as you don't want to be making a trip back to Dangling Rope if you don't have to.
The other thing you have to think about is the running condition of your houseboat. If everything runs smoothly, it can be a enjoyable trip. My last trip with the houseboat (may old one), everything seemed to be running fine when we got on the boat. Going down, about Hole in the Rock I had one engine act up. Ran off/on until the mouth of the SJ, then it was all "off". Had a mechanically inclined crew, and LOTS of spare parts, tried everything we could and we couldn't get the engine running.
Which meant we had to go back on one screw. Not the end of the world. Until we got to Escalante on the way back, and then the good engine started acting up. By the time I got in front of the Halls Marina it was very tough going - actually took two hours to get from Halls to our slip in Bullfrog. That was a LONG trip back.
So, if your boat has the legs to do it, and you and your crew have the stomach to spend that much time traveling, and the cost associated with it, and a strong running boat, and you have say a week to dedicate in the SJ, I say go for it. Just know what you are getting into.
And that doesn't take into account the White Walkers, zombie horses, crocs, or other perils up there.....
Finally,
@WaterMan EVERYONE knows that the high inflows this year pushed all the fish downstream......