"...how are you going to store it..."
Well, besides the fact I now have a 9x6m shed, I found that the shift to 15mm helps.
I picked middle eastern terrain as it has a 'timeless' feel can be used for any action from 1500 to 2500AD.
I bought enough from JR Miniatures to fill a small 4 x 4 table (perfect for Force on Force) which cost around $100 - which barely buys two 28mm buildings.
Here are some of the buildings (unpainted):
I feel terrain is a major sticking point - good terrain 'makes' a game but I seldom have the enthusiasm for terrain-making as I do for painting - this is definitely going to inspire more 15mm games...
For 28mm, I have ordered some Terraclips from Wyrd Miniatures
It is fantasy-focussed (for their game Malifaux) but looks really good quality. It is card based (similar to Space Hulk/D&D tiles) but clips together and can be 'layered'. It's like LEGO - you can make any setup you want. For $50 a pop I think it is real value and versatility.
Here are some unboxing vids showing how they fit together:
Unboxing & Assembly
I like how they store easily in a box, flat.