Davena,
From what you're sharing I'm wondering if the Emerging Reader books are too difficult for your little guy? Harold the Purple Crayon and Morris the Moose are much easier books than Wagon Wheels and Buffalo Bill. There is a gradual move during the Emerging Reader set to more difficult books, and right around Wagon Wheels, Amelia Bedelia, and Buffalo Bill is where it jumps up a bit. I would set aside the Emerging Reader Set for awhile and see if you could use more Frog and Toad or Level 2 type books for a month or two. If you have access to a good library or a local bookstore, you could stay around that reading level to give your little guy time to mature as a reader. Sometimes kiddos hit an incline in reading level that feels too steep for a bit and they shut down.
As far as the reading aloud goes, if your kiddos aren't enjoying the storytime books, it is most likely due to the fact that they're not quite ready for that type of longer read-aloud without pictures yet. If you haven't had a chance to read-aloud the Storytime set from LHFHG yet, I'd encourage you to do that instead. It is a great transition to listening to more difficult read-alouds. You could just read a chapter a day until you're through that set. Be mindful that you won't have the plans in LHFHG to go along with it, so you'll want to do some guided talking about the books on your own. The characters in the Burgess books behave very much as children do, and learn from their consequences just as children do. They're certainly not perfect characters, but they do a great deal of learning from their mistakes.

While your kiddos probably will need to grow into listening to the Burgess books in the Storytime set too, it will be less of a leap than the books scheduled in Beyond. Plan on giving the Burgess books 12 weeks to grow on your kiddos too, but you will see the fruit of your labors! Just be very excited and upbeat about it yourself, so your kiddos can take their cues from you.

Also, make sure to keep on perservering to the end of the book, or kiddos begin to think they can get out of finishing if they act disinterested enough. Kiddos are so perceptive on how to get out of "work"!
Listening to harder read-alouds is a skill that takes some time to develop. It is actually hard work, and isn't beloved by all children when learning to do it. Eventually, as the skill becomes easier, kiddos enjoy the listening to books read aloud more. I'll just encourage you that it takes time for kiddos to develop the skill, so don't expect your little ones to beg for more right away. I'll also mention that when asked most young kiddos won't want to continue reading. They'd much rather play than do something they perceive as work.
Hang in there! It will come. It is a skill to be learned just like reading or math.
Blessings,
Carrie