I'm a commuter who wants to do occasional long rides; what bike should I get?

My personal belief is that there are 2 main types of bikes (ignoring mountain, "cruisers", and tricycles) that you might consider and buy them unique for each scenario. Now, obviously there are exceptions for that due to pesky constraints ($) and it's quite possible to make do with one bike for multiple purposes. In fact, my first ride was gifted to me and I used it for almost a year as a commuter and a long distance road bike. Given how much I ride (and love it) I have found that having specialized uses makes me happiest and that for me it makes the most sense financially (based on risk assessment). 

I'll list off my views and you may note where the conflicts lie. Whether you are looking to specialize a ride or to try to make a hybrid, it should point you in the direction of the most important characteristics from my viewpoint.

COMMUTER

• Avoid getting stolen
• Should not be too "flashy"
• Skewers and other parts should require tools (read: not quick-release; hence slow to change a tire)
• Should have only cheap or secured lights attached (expect things to be stolen if they aren't secured)
• Reliable/abusable
• Bullet-proof tires
• Heavy is ok
• Not cost too much in maintenance over years of Boston weather
• Fewer parts = less maintenance (read: fixie/single-speed)
• Comfort for short distances

LONG RIDE

• Easy to change a tire/parts
• Easy to steal parts if you leave it somewhere, whether locked up or not
• Comfortable for long rides
• This may cost more for the right saddle and for parts maintenance
• Lighter weight becomes increasingly important across frame and tires (although I still buy heavy, bullet-proof tires)
• Should be equipped with a tube changing kit

If you're like most people, it seems that you're looking to make a cheap Long Ride bike work as a Commuter. Given that, please note the abuse the components will suffer from weather and that I recommend getting skewers that make your wheels harder to steal. Essentially, make sure things are locked down, and then when you go for a long ride, bring the tools to unlock it. You may want to be diligent about cleaning the chain every few weeks to extend it's ease of use.