Last weekend my family went out of town leaving me home alone, so of course I planned to ride a ton of miles. I planning to do two Long Rides: to Alabama and back on the Silver Comet Trail (122 miles), and then Airport Long with additional miles added at the end (84 miles)
I would consider any ride over 80 miles, 5+ hours, largely solo (i.e. no supported rides such as Gran Fondos) A Long Ride. Some people hate the long ride. It's boring. It's tiring. What's the point?
I love The Long Ride. Especially rides longer than 100 miles. For several reasons:
YOU DID SOMETHING Sure, you can go out for a 40 mile training ride that might be harder than (and better for actually getting faster) than a 120 mile ride, but there's something about the sheer distance that makes some of us feel like "man, I really did something today."
EAT & DRINK!!! One of the best parts of doing a huge amount of miles is all the food you can eat. I also like to consume more than is a reasonable number of beers.
BUILDS ENDURANCE Doing very long rides also helps to build endurance. It helps to be aware of and anticipate symptoms you might experience during longer road races (sore lower back, butt pain, hand pain, etc). It also helps to harden you against being bothered by those things.
ENDORPHIN HIGH I can't really put my finger on it, but for the rest of the day and sometimes into the next day following doing The Long Ride I feel tired but a bit like I have a runner's high. I'd imagine it's from endorphines doing their job. Regardless, it's a good feeling.
TIME TO REFLECT Most of the time I don't actually think about anything while on the ride, but a few key ideas generally keep floating around and sticking in my head. Is this a good thing? I don't really know, but choose to think it is.
I recognize The Long Ride is generally a bad idea for training. Unless you're a pro, there's not too much benefit to doing 120 mile training rides. Especially if you put two or more of them together for a training block. It just wears you down without making you faster. Most racers will need a recovery week just to get back to the strength they had going into the block, so you potentially lose a week of building speed.
So if possible, when a situation arises that I can do a weekend of Long Rides like last weekend, I just try to schedule it at the end of a build period that needs a rest week following it anyway. That way I can enjoy myself without derailing my training plan too much.
But regardless, I would do The Long Ride even if it gets in the way of my training plan, just because there's something special about it to me that I really enjoy.