Before buying a giant chainring, my suggestion is to get a smaller rear sprocket. By swapping out your 25t for 23t, you can buy some extra top-end speed. Then, when you do choose to get a bigger chainring, it won't be as big.

The only place that seems to have the 23t in stock is www.biketoolsetc.com (you'll have to call them, its not on the site)

For the Mini, you definitely want Schwalbe Big Apples. At 70psi, nothing will roll as nice.

On the 8H, you won't need as big a chainring due to the larger wheel size. Again, start with the 23t sprocket and see if that works (you won't need a new chain)