Migs,
1/48 and bigger can be an incredible experience - imagine creating a model with real moving parts - we're getting close to miniature engineering, not scale modelling. That's the true test of your modelling abilities - can you make it look AND function EXACTLY like the real thing? Not as easy as it looks.
Plus, aside from the ease of assembly that the previous respondants have indicated, they bloody well look impressive.
Have you ever gone to the Smithsonian and seen their large scale models? They have an unbelievable amount of the WOW factor.
You can see very clearly how structures were assembled and that helps with understanding how thinks work, which has always been one of the major reasons why I find scale modelling fascinating.
There is also a massive amount of detail that you can cram into these large scale models - that in itself can be amazing if the detailing is well done. Gives the eye hundreds of things to look at and keeps contest judges very busy.
I make all sorts of things in all sorts of scales - I love the variety of aircraft in 1/72 and 1/44 scale, but I also love the much larger scales.
I find the only real problem with the big scale stuff is that the model sometimes ends up turning into an epic adventure - two years after starting and "it's nearly ready to paint!!!" - yegads. I hate that, and do it all too often. So with the contract building I do, and the fact that I do so much work on one model, I end up finishing one or two models for myself (if I'm lucky!) per year.
Such is life.
Cheers,
LeeTree