Wow, I'd never heard of CitiesXL 2011 - thanks for the pointer.

You can do street layouts in a variety of ways in CE.
You can draw the streets yourself (adjust street width on the fly) you can have pavements/sidewalks if you wish (again you can adjust the width)
You can import a DXF image of a streetmap, but CE will ignore the width of the line and set them to a single default 'major street' width which you will have to adjust manually to make minor streets (select street, type a width value or use a slider).
You can get CE to generate a street pattern for you based on simple principles - radial, grid or organic. There are lots of options on max street length, splitting etc (although not as many options as in RPG City creator).

You can do a combination of the above, so for example you can draw your major roads and then get CE to generate the minor road network inbetween them automatically and then edit afterwards.

Modern cities are much easier to do, only because streets are less wiggly and the buildings are more uniform which makes them easier to texture. One thing I do like about it (haven't tried it yet) is that you can use map 'underlays' to provide building attribute probabilities. For example: If you want taller buildings to occur more in the centre of the city, you have a map underlay (say black on white) like a layermask. You can tell city engine that the darker an area on the underlay, the more likely buildings there should be taller. Or you could say that the darker the underlay the more likely they should be tudor style buildings in that area. That way you can define neighbourhoods quite well (that's the theory) - as I said, I haven't got to playing with that bit in earnest yet.

There is just so much in this software to learn, but most of all the biggest learning curve is the cga language to make buildings and texture them. Again, quite straightforward for modern skyscrapers (which are mostly just cubes) but a bit more challenging with older, more ornate styles. If you need a 'one-off' building (e.g. a Colosseum, Palace, Castle etc ), you would probably build those using a 3d modelling engine and drop them into the map rather than building them using procedural code...although eventually I would like to be able to make simple procedural castles.