Hello,
While my kids are still pretty young (almost 2, 3 1/2, and 5) I have worked with all ages and in some ways kids are just like adults - they want to have a say in what goes on. To get your kids to buy into longer rides I would suggest that you allow them to make some/many of the planning choices.
Get your older daughters to look at maps with you. Give them a few options to choose from and have them decide how far they want to go and where. You can let them decide on the snacks to bring and let them set goals on where to try to get to before snack stops. They can be aware of what the landmarks are that they will pass. You can even make a list of the landmarks and goals for the oldest kid to check off as you go. Also, creating a checklist of gear and stuff to collect for each trip would allow your kids to help with the prep. Through this planning they can feel like it was thier trip and they can have a stake in it feeling successful. I think that sometimes as parents we do better to let go and go along for the ride rather than to ask our kids to be passive group members all of the time.
There will likely be times that things don't go to plan and how we parents handle it is key to future interest from our kids. We usually learn more from the difficult times than the easy ones...so I try to think of the hard days as good learning opportunities. I suggest making a habit of a group meeting at the end of each ride that asks simple questions: 1. What was your favorite part? or What went well? 2. What could/should we work on next time to make our rides even better? 3. Does anyone need any repairs/ gear changes? If things get particularly hard on a a ride stopping mid-ride to have an impromptu meeting with snack can give a chance for re-assessment of plans and make everyone feel cared for. Also, the re-energizing power of silly songs, bike bells, and simple games should be remembered and kept ready in your back pocket.
Last thought, not every ride should be a long one or they might look at getting on the bike as a big commitment of time and effort. Are there short errands that you can do by bike with your kids? We do small grocery trips by bike, post office, pre-school runs and play grounds by bike. We as a family have committed to doing everything that is within 2 miles drive by bike assuming 1/2 way decent weather and no safety issues in route. This daily short rides make the bikes a normal thing for us and the kids look forward to the time together and outside. My daughter asked me the other day (2x on the same trip) why we didn't bike to costco.
Good luck.