For a while now I have been trying to find the perfect bike. One that is fast and allows me to ride 20 mph for 50 mi. One that I can load stuff on and has braze-ons for racks, fenders, etc. A bike that does not punish you for riding more then 40 mi.
So my question is does this bike exist? Is there a bike out there that will suit all of my needs or will I need multiple bikes for every occasion?
I think that it is generally true that any "all-purpose" tool is less-than-ideal for most purposes. There are trade-offs for everything.
If you are just looking for a bike that allows you to ride fast and long while carrying a load, though, I think you are looking for a light touring bike. Get something with drop-bars and road-y geometry. Get a comfortable saddle for it--maybe Brooks B17. It will go reasonably fast (not racing-bike fast, but certainly faster than my Globe Vienna).
Personally, I am not following my own advice--I am doing what you suggest on a mid-80's Schwinn steel road bike. I have racks and fenders on it. It goes not-as-fast as my racing bike but fast enough for sure. When I routinely carry lots of heavy loads on it, I start breaking spokes but that's the wheel's fault and not the frame. The old steel Schwinns really do never break--if you put the right components on them, they will haul anything you want.
At some point I may replace the Schwinn with something more modern. After all, I'm running it with old 105 gear and down-tube shifters. Generally fine, but when I can afford it I'll upgrade. My Vienna has started to spoil me, with its IGH and shiny paint.
In your position, I might consider a Civia Bryant. Go with the belt-drive option. It can haul a load, go fast, seems comfortable (having only looked at the geometry), and is low-maintenance.
Long distance? Carrying stuff? Speed? It sounds like you are describing a Touring Bike. I know that the Surly Long Haul Trucker is a popular model, but just searching for "Touring Bike" should give you a number of different options.
A touring road bike or, better, a cyclocross or light touring bike is probably going to meet your needs.
Be aware that riding 50 miles in 2.5 hours will be unreasonable on any bike without a tremendous level of fitness. As folks say, it's more about the engine, than the bike!
Instead of finding a fast bike that will haul stuff well, consider getting a fast road bike and a trailer. You'll then have a bike unencumbered by racks that you can use to haul a trailer. There are still questions of the proper drivetrain configuration here -- I'd avoid a delicate 9-speed drivetrain, for example. You can also attach a seatpost rack for commuting.
The good news is that you're willing to compromise on price. That means a fairly light, fast bike that is comfortable and can carry loads is very doable. If you prefer an upright you could buy a titanium-framed touring bike and build it with decent components, probably ending up under 10kg for the complete bike (without panniers).
A better solution IMO would be a recumbent, also a touring bike, but with suspension and a much more comfortable seat. "more than 40 miles" is easy on most recembents, so you can shop through the faster ones looking for a match between fit and load capacity. I would be looking at something like the M5 Shockproof 559, or HP Velotechnic Streetmachine, or Bachetta Giro 26. Recumbents will be heavier, but much more comfortable and faster (except uphill). You can spec those up to a considerable degree from the base machine, because the bikes are built to order.
I've had great luck with old Trek mountain hardtails (Trek 820, 930) retrofitted with road tires. I've been commuting daily on these for quite some time. They support racks and fenders and can be found for relatively cheap on Craigslist. A good friend of mine toured Alaska on his Trek 930 (fitted with fenders, racks, toe-clip pedals, and an extra water bottle holder).
I bought a Trek 820 for $105 on Craigslist and it's been great (albeit after replacing several parts - pedals, seat, tires - to name a few, and getting it tuned up and tightened).
I lucked out and purchased this exact bike off Craigslist from the man who built it. It wasn't necessarily cheap, but considering it's done the job of three bikes, I've felt exceedingly lucky to have found it.
It's a Surly Pacer frame, full Ultegra 9-speed grouppo, and a Brooks B17 Standard saddle. I use 700x28c Panaracer Ribmo tires which have lasted for 3,800mi (6,100km) without a single flat. I can and have attached fenders to it (even on tire sizes up to 32c, I believe), although I leave the Race Blades off unless it's raining. The only thing I needed to do to add a rack was to buy a pair of P clamps, since it doesn't have a pair of braze-on eyelets on the seat stays.
The bike clocks in a bit heavy at 30lb (13.6kg), but I have no problem keeping up with the Faster Mustache Road Ride (30mi [48km], 17mph [27km/h] avg, 3,100ft [950m] of climbing) and the Airport Ride (50mi [80km], 25mph [40km/h], no climbing). It took my wife and I through 500 miles of touring from Amsterdam to Paris without the slightest problem, outfitted with a rack and two heavy panniers. And I commute on it daily on the poorly-maintained and pothole-stricken streets of Atlanta.
I think this is close
A titanium CX with rack bosses / braze-on
Yes titanium is more expensive but if it replaces two bikes then about the same cost
I like the shorter wheelbase of a CX but it limits the size of the rear pannier
What you get out of touring bike is a little more length
But a touring bike is going to (typically) be heavier and less nimble
Not cheap but you can order braze on on a Moots Routt
There are some light touring bike out there like Salsa Vaya that take racks and fenders
And there are some commuter carbon frames coming out with rack and fender bosses like a B'Twin Triban
Look into endurance bike but those are still more race oriented so hard to find rack / fender bosses
