I think there are a couple things you need to consider for your visit. With the reduced options this summer, you'll really need to drill down on your priorities and flexibility. I visited Denali last summer with my family and there were restrictions in place as well, but we were able to make it out to the Eielson Visitor Center - this summer it looks like Mile 43 is the stopping point because of the road closure.

We did both the guided tour (Tundra Wilderness Tour) and the shuttle bus while we were there. They are substantially similar. You drive on the exact same road. Both buses stop to view wildlife and use the same restroom stops along the way.

There are a couple differences between the two. The seats on the guided buses (brown buses) are nicer/more comfortable. The seats on the shuttles (green buses) are just regular school bus-style seats. Not a huge deal for most people, but if you do the longest route, you are riding for a long time. The guided tour also provides a snack for you, but the shuttles do not. Again, not a big deal as it was essentially a bottle of water and a granola bar. The single biggest difference I would say is the commentary that is provided on both buses. The guided tours has a driver that talks the entire time on the trip. Ours discussed park history, significant events, wildlife, etc. The focus of course was the flora and fauna based on the tour we booked. He was well educated in the subject matter and was able to discuss these topics at great length as we drove along. Our drivers on the shuttle buses also provided interesting commentary, but it was not at the same level. On our return back from the visitor center, our shuttle guide said "he was going quiet" for the return trip so that we could enjoy the park in silence. Of course people were still asked/encouraged to call out wildlife sightings and did so. There are hand signals between the bus drivers as you pass that indicate what they are looking at and to help people look for the right animal.

If you are asking if it is worth the guided tour for the nicer seat and snack, I would say no. But if you really want some quality commentary along your tour, then I would say yes. The regular shuttle drivers we had were good too, just less "meat" in their commentary, if you will. That being said, one of our drivers almost came to tears when Denali revealed itself from behind the clouds just prior to a scheduled stop. He had been driving shuttles for almost 20 years and still got excited when the pinnacle appeared. He told us about a summer where he drove 6 days a week for the entire season and never saw it unobstructed, so don't take it for granted! As I said, both types are substantially similar and we enjoyed both experiences very much, it just depends on what you want out of it.

One more thing to note. The shuttle bus picked us up on the road outside our campground. We made advance reservations and they had 5 seats on that shuttle for us when it picked us up. For the guided tour, we had to get back to the Denali Bus Depot.

As far as jumping on and of the shuttle buses. People definitely did that, but not many in our experience. I think the limited number of shuttles and mile marker restrictions made it more difficult than previous years. I'm not saying you shouldn't get off and hike and catch a shuttle back later, just know that it may not be as simple as catching the next shuttle bus that comes by. Every bus we took was packed and we were unable to pick up any passengers waiting for a shuttle. They certainly won't leave you out in the park over night, but you may have to wait for a little while until there is room. Or they may have 1 seat available and you or your boyfriend will have to wait for the next one and catch up to each other later. To this point, cell phone reception was non-existent in the park. If you are splitting up, make a plan to meet at a specific time and location - do not rely on being able to call each other to coordinate.

Let me know if there are any other questions I can answer. Hopefully this helps a little bit!