L'Arc-en-Ciel (there is also a very popular boy band of the same name) is one of the more popular cafes located in the depths of Umeda Station, and can be a good place to rest with some coffee and a piece of cake (¥800) or sweet waffle (there is currently a bit of a waffle boom in Japan). Coffee shops have long been an important part of urban Japanese culture, however there is a big stylistic difference between the coffee shops frequented by middle-aged businessmen (known as 'kissaten'), and those popluar with young people ('kafei'). Kissaten are populated by housewives and retired people during the day, and, depending on the neighborhood, businessmen and hostess girls looking for extra gifts/cash at night. Cafes are new, clean, Euro-oriented, and fashionable in a pleasant way. L'Arc-en-Ciel falls squarely in the 'cafe' category, and the clientele are predominately young, single, working people, who incedently smoke just as much as their parents, even more in the case of young women.
For a smoke-free cup of coffee your choices are vending machines or Starbucks (which has maintained its non-smoking policy abroad). For a cheaper cup of coffee try the Japanese chain Dotour. For ¥180 you can enjoy a great glass of super strong, bitter ice coffee that tastes a bit like Vietnamese iced coffee without the condensed milk.
L'Arc-en-Ciel is two levels beneath the "Big Man" screen in Umeda Station. Again, this is a great time to ask the information girls which way to go. If it's too crowded (weekends are busy) or not what you are looking for, there are numerous other choices nearby, and wandering around you will doubtless run into them.