After considerable experience owning/using various sized telescopes, I have decided that a 16" scope represents the "sweet spot" for my observing style and fairly large physique.  A 16" scope offers decent light grasp-- frankly, more than my mediocre skies can take full advantage of on most nights, which is a backhanded way of saying I'm well positioned to see as much as possible when the atmosphere does cooperate!-- yet can be made compact enough so that 6' 2" me can see through the eyepiece at zenith flatfooted or nearly so.  I own and have extensively modified a solid tube-based 16" f/4.5  Frankenscope, which I purchased as my first large aperture scope.  The Natasha project (see the bottom of the main Amateur Telescope Making page if you're curious about the name) grew out of a plan to upgrade the primary mirror in that scope from a good Meade piece of glass to a premium optic.  In the year between ordering the mirror and receiving it, not only did I come to realize that this was the perfect size for me, but the resulting 16" mirror from Obsidian Optics (http://www.obsopts.com/specs/SN0322.htm) turned out to be so good that I didn't want put it in Frankenscope, since that design uses mirror clips and the edge on the Obsidian glass was so good that I didn't want to degrade the image in that fashion.  The big downfall of an f/4.5 instrument is coma, which I'm pretty sensitive to, but certain eyepieces seem to minimize it (the Meade 14 Ultrawide is one such), as does Nagler's Paracorr (especially with the Nagler 31 eyepiece-- I call this combination "the steamroller" because of its flat field).

Natasha was destined to be a truss tube instrument, since I had a copy of Kriege and Berry Dobsonian telescope book (http://www.willbell.com/tm/dobtel.htm) that I'd been planning to use to guide my construction of my 10" travel scope "Igor".  "Frankenscope" is a sweet instrument, and probably the only Meade Starfinder that was ever modified to become substantially heavier than the stock configuration (fully set up it probably approaches 300 pounds).  This is no problem for me (the scope breaks down into four loads, plus I think benchpressing 450 pounds is "fun") and made for a very stable, windproof scope, but even I'll admit that sometimes at 3:00 AM on a winter's night I'd appreciate something easier to put away, especially if I am in the field and faced with dismantling the base and stowing everything in my car. (The scope was designed to fit in the Ford Taurus station wagon I had then, and it fit snugly, but would only go with all of its' pieces put in a certain way, like a jigsaw puzzle.) 

There was also the issue of a truss tube scope taking up less room in the car, though there turned out to be less space savings than I'd anticipated.  Most of Frankenscope's parts stack vertically in a car, plus through practice I'd found ways to fit it, the 10" LX200, a solar scope, an easel, whiteboard, and teaching supplies, weekend's worth of camping equipment and food into the car when teaching the Astronomy merit badge for the Boy Scouts.

Natasha set up in the field