Both chains provide reasonably great free wifi service, which is a huge benefit if you travel a lot or your DSL service is not that great at home.
On McDonald’s, if you just want to use wifi very quickly for almost no cost, and money is an issue. You can buy a medium cup of coffee at McDonald’s for $1.00. (You can get a bagel at Starbucks for $1.00, but there are no drinks for that amount.) However, if you are at McDonald’s, make sure that your battery will last the duration because there are generally no power outlets at McDonald’s, and make sure that you are totally engrossed in what you are doing because the tables and seats are one size fits all. The Golden Arches does tend to have larger locations with plenty of seating though.
Starbucks will give you greater comfort, a better table and seat, and the ability to recharge. Some Starbucks even have couches. Starbucks is also more upscale and you can feel pretty comfortable running to the bathroom for a couple of minutes is no problem. You can generally leave you belongings lying around, although I would recommend at least taking your wallet with you to the bathroom. The least expensive cup of coffee at Starbucks is close to $2.00, and I am sure that the average cup is much more than that.
If you are a night owl, you might want to check your location and plan to do this over the course of a week when you are visiting, you will definitely want to check out the seating. In Chicago, both Starbucks and McDonald’s have locations that are open 24 hours a day, but the North State Starbucks location becomes very crowded. No such problem at McDonald’s on Chicago Street. In San Francisco, the California street location becomes very crowded with students late at night. In New York, there are a couple of locations that are open in Manhattan around the clock, but there nothing that qualifies as seating. This is important because if you stay for any period of time, you definitely want seating.
Overall, I am very happy that free wifi is getting to be the normal rather than the exception. San Francisco International Airport recently started providing wifi for free. Some places like Barnes and Noble always seem to be crowded in every city. Quite honestly it was getting kind of ridiculous the number of different accounts that I need to maintain on the road before I discovered Tether www.tether.com. Things have been much more pleasant since I discovered Tether.
For other free wifi locations, try http://www.wififreespot.com/companies.html. This is a pretty extensive list. Good luck.