Good luck with the weather continues: warm, dry weather that is great for riding. We're already into the first week of October, and though the daylight is getting shorter, the weather has been cooperative so far.
I recently took out this 1957 Schwinn Traveler three speed for a nice, evening ride. Schwinn's version of the three speed bike just has a durable, solid feel to it. Granted, it's quite heavy for a three speed bike with a diamond frame, but it has a durability and "substantial" feel that is hard to match.
The Weinmann 810 brakes ("Schwinn Approved" branding on the caliper) were ahead of their time when you consider how lightweight they are and how intuitive they are to service. I will grant that they can be a bit fiddly to adjust, but once they are dialed-in, they're great.
This time of year you need a good set of lights. This bike has a Kily/Soma retro headlight (LED in a vintage-style chrome metal shell) and taillight (LED Soma stainless steel torpedo rear).
I recently swapped the handlebars to a set one size larger (22 inches across with a little more rise and pull back). I wanted a little more substantial set of bars, but not something overly large. I think these are a great balance of control and compactness. Some of the later 1960s and 70s bikes had oversized bars as would be found on a cruiser type bike. I think those are a bit too big for a bike like this. These medium bars are quite comfortable and give good control when taking a sharp turn or hitting a bump.
I wrote recently about frame weights on vintage three speed style bikes (see HERE). This bike is an example of when weight is only one of several concerns, and where it is fairly far down on the list of priorities in building a bike. Yes, the Schwinn is "heavy" for this class of bike, but the weight really is not a bother when you consider how comfortable and durable the bike is.