Electrolyte tablets are good if you’re sweating a lot but I don’t bother with them if I’m eating normal food. Also I’m not sure about having them before…I’d have thought use them during or after.
Gels are brilliant in a race or on a fast paced effort but I’d try to stick to normal food for day rides at a lower intensity. Gels are pretty much just sugar, so you’re not getting any nutrients from them (and you’ll be needing more nutrients than normal because you’re riding all day!). I like Sandwiches, maltloaf, teacakes, bagels, that sort of thing. I would definitely carry a gel or two in case, though – they really get you out of trouble fast if you run out of energy.
If you are concerned about running out of energy due to succesive days riding, I’d recommend a carb drink in your Camelbak to supplement “proper” food, that will keep a trickle of calories flowing in if maybe you have a long haul between food stops.
Also refuelling after the ride is really important for multiple days on the trot (you want to make sure your glycogen stores are topped up for the next day’s riding). You might finish a ride and then go out to eat with your buddies 2 hours later and miss your refuelling window. Rego is great for this as it’s easy to get down at the end of the ride and you don’t need to worry so much about preparing something to eat in a hurry.
Have a great trip! Colorado is an absolutely fantastic place to ride.