For me, front mudflaps are the first item to consider for keeping muck off the chain and bottom-bracket area.
I've also noticed that the chain stays a bit cleaner on bikes with rear hub brakes rather than rim brakes (in my case coaster, roller or drum brakes, but I reckon disk brakes should be the same). The worst rim brakes are those mounted near the bottom bracket, which are placed in just the right position to spray muck all over the chain. My old mountain bike had one of these, a U-brake, which probably accounted for the excessive chain wear I experienced on my 2011 tour.
Bikes with hub gears stay cleaner (chain not so close to the road) and are easier to clean than derailleur gears (fewer sprockets, no derailleurs). If the chainring/sprocket combination is compatible they may also allow a Chainglider, which I reckon is the best solution for keeping the chain clean and reducing maintenance.