When I think about shoes with jeans, two types of shoes immediately pop into my head: loafers and boots.
Tie Loafers — These loafers basically scream summer without appearing too checked-out. They are the best option if you want the comfort and ease of a boat shoe but a more polished presentation. As with most shoes, I would prefer them in suede. Carmina has an excellent snuff suede option, as does their loosely-related cousin Meermin. If you’re looking for more Italian flare, you can also have a look at sloops. Will at A Suitable Wardrobe currently has some on sale. I’d go with the mid-brown water buffalo.
Penny Loafers — A traditional standard, penny loafers can look great with jeans. I’d just recommend staying away from the usual brown calf or burgundy calf and get a little more creative. Suede in snuff, sand or chocolate brown are always a great play, with sand suede being the most “summery” of the three. I personally own two pairs of non-calf penny loafers, one in Russian Reindeer Calf and one in cigar shell cordovan. While I love both and would highly endorse either, I think (for spring and summer) a lighter suede would add a nice bit of texture. Check out Rancourt, Oak Street, Sid’s, and Brooks Brothers (currently on sale, mind you) for some solid options.
Driving Loafers/Moccasins — There are many people that will tell you that driving loafers should only be worn for driving. These people are also likely to wear formal day dress to a business casual luncheon and judge strangers for wearing blue shirts after 6. Unless you have a private track in Tuscany, no one should own shoes specifically for driving. Are they practical? Not in the sense that you’ll own them forever. However, they are easy to wear and incredibly versatile. I just wouldn’t spend top dollar on a pair as they can’t be re-soled and get torn up pretty easily. For a cheap option look to Brooks. If you want to spend more go with Sid’s — they are made in the same factory as Car Shoe and Bottega Venetta and are a little less expensive.
As I type this I am wearing jeans and boots in the office. My particular shoe at the moment is a wax-flesh moc-toe chukka by Quoddy (MTO from Leffot). However, I also wear my RL Saunders constantly and would recommend them in an instant. Finally, you can also look into a Chelsea boot. For all of these I would stick to either snuff or sand suede. I prefer snuff because it can be worn with denim, grey wool or khaki cotton. While sand suede is more “summery,” I find it’s a bit limiting and can be jarring when paired with a less-than-summery ensemble. Best to stick with a more neutral color and texture.
While boots may seem an odd choice for summer, buying a pair in a Vibram or crepe sole makes them a lot more casual, as well as lighter-wearing. Alden’s flex-welt is a prime example of this. Buy a pair of unlined chukkas and you’ll be just as comfortable as any of the other options above.
While you didn’t ask me about this directly, I figured I’d weigh in (giving unsolicited advice is a strong-suit of mine). You mention dark denim. While dark denim is thought of as “more formal,” I wouldn’t limit myself to only inky, raw denim on Fridays. Especially in summer, you can get away with a more casual look. I’d recommend looking at some conservative washes like RRL’s “once washed” or Raleigh’s vintage wash. You don’t need to get into dad jeans territory, but having stiff, rigid denim doesn’t really fit with an airy summer look. Just my $0.02.
Hopefully that helps a bit. Happy hunting.