As inspiration, I'll take the liberty of outlining the rack I am building at the moment. It isn't a terribly large one, but it should be respectable enough, and I dare say it is a convenient solution when the goal is to have a convenient stereo rig with all the normal effects in it.
There are a couple of reasons why I chose to go for a rack set-up. First of all, I find that there is something strange about people keeping very expensive pedal boards at the very front of the stage, where they are subject to all sorts of hazards. Secondly, I am very fond of the idea of a wet/dry, or even better, wet/dry/wet, rig, and to set this up with a more conventional rig is not only far more complicated, but more things can go wrong. Racks allow for shorter cable runs, with cables being put permanently in place, and this (contrary to received wisdom!) results in fewer things to go wrong and easier troubleshooting: for instance, you might need 10 stomp boxes to replace a high-end multi-fx unit, and those are (in a best-case scenario!) going to be carried in and out of a board where all the cables are likely to be subject to considerable friction from transportation and, indeed, being stomped on.
I am currently working on putting together the following rig:
Preamp: ADA MP-1. This is arguably the most famous rack pre-amp for guitar of all time, and should need no introduction. I still don't think anything else quite gets that sound.
Effects processor: TC Electronic G-System. This was, for a number of years, the flagship system from TC, which promised to cater to all effects needs both in a rack and a pedalboard format. I ended up going with it for the simple reason that I liked the idea of a dedicated midi controller that was included in the price of the unit. This unit basically contains every needed effect, put them before or after the preamp in the most conventional set-up (but see comment below). There are some caveats to this unit: it is known to be somewhat mischievous, and demands serious attention when setting up. Something like the Line 6 Helix could probably do the job as well today, but it is 3U large and in an entirely different price range.
Pedals: The G-System does not have any gain stages, but includes four bypassable loops for pedals. These are convenient for different reasons. The G-System has one section that goes before the preamp, and one that goes in the FX loop or between the preamp and power amp. The only problem is that one cannot really change where different effects go: you are stuck with the phaser in the loop, for instance, which is no use when you want that crummy EVH phaser sound. I will be using the following pedals:
Boss OD-1: Still my favourite boost
Boss DC-2: There is nothing quite like this. I love how the effect really shines through clean, and recedes into the background when distorted. I will not be able to use it to its full potential: this should have been in the loop, and split the signal wet/dry, but there is just no way that is going to happen, since the pedal has so little headroom.
MXR Phase 90: Because we all love a LO-FI phaser every now and then.
Wireless: I have a 10 y/o Shure half-rack system that I was planning to use as the basic system. If this doesn't work, I will look into some of the higher-end Line 6 systems, I think, as they are readily available locally.
Shelving: I will need a 2U shelf to keep the pedals on. If possible, I will also put the wireless system here.
Noise gate: There is no way around it: the ADA is a noisy beast! I will try to live without it, or use the TC gate, but many people seem to prefer to use the ISP Decimator.
Power amp: For now, I will use an old Marshall 9040 power amp. This is a solid state 2x200 watt amp, that seems to work passably well. I have a Marshall 9100 power amp with EL34 valves as well, but to me, the added weight and frailty of that unit does not justify the added weight and costs (I would have to get a sturdier rack for it). Some of the "cut" added by tubes can be emulated using a BBE Sonic Maximizer (as did Vito Bratta back in the day).
Speakers: 2 2x12s with Celestion Greenbacks in them. These might be put in the same 4x12, with the majority of the stereo effect eventually being created by the sound guy.
I plan to put this into a 12U rack, organized like this:
2U: Shelves, including wireless
1U: ADA MP-1
1U: Decimator (if applicable)
1U: Sonic Maximizer
2U: Marshall 9100
That leaves us with 8U used. It is beneficial with a little extra space both for the purposes of extension and heat dissipation. The lack of a tube power amp means that I can get away with not using a shock relieved rack, which should lighten the whole rig significantly.
The signal chain would be as follows:
G-System part 1
G-System part 2 (split into stereo)
The MIDI set-up should be easy, since the ADA is the only MIDI-driven unit apart from the G-System, and I only need to use a few patches on it.
Future changes or extensions:
I have a Boss SY-300 that would have been very fun to include in the rig. This would demand a separate power amp, a a separate speaker, and probably a new 2U shelf.
I might ditch the 9040 eventually. One possibility would be one of the newer Matrix power amps. These are supposed to be optimized for emulating tube-like tones. Whether the hype is to be believed or not, their 1500 watt power amp (500 watts * 3 channels) is only 1U, far lighter than my present power amp, and would allow for easy integration of the SY-300.
If I win the lottery I might try to get a Soldano HR 25, run this straight into the cabinet and run the rack as the effected sides in a wet/dry/wet rig. Oh, one can but dream.
So that's it. It is actually a deceivingly simple rig once looked at closely, but it supplies all my needs in a more convenient manner than a typical pedalboard-and-amp rig, where I would have needed two heads and a number of long pedal runs to and from the amps.
Final note: if you are genuinely interested in rack rigs, you could do worse than invest in the book Modern Guitar Rigs by Scott Kahn. The book is not perfect (it is getting old, and at times reads a bit too much like an advert), but will give you a decent overview of the types of rack units available out there today, and what you can expect them to do. Warning: going back to a conventional guitar rig afterwards might be difficult!
No longer looking for a late-era Baretta I body (with double scooped lower horn).
Great trades with: bacon