In typical SQL style actually the answer is "it depends" - on how you work.
Hovering the mouse may be quick but not that helpful since as soon as you start typing the list tooltip disappears so if you want more than one from a table with quite a few fields and you really can't remember then that blows that out the water.
I have widescreen monitors (doesn't everyone nowadays?) at 1920 odd res so I have object explorer permanently pinned open. Further when I am working with a particular database (I'm a software dev) I expand Management Studio and typically have either tables or the programmability sections (or both) expanded so for me at wors it is a little bit of a scroll and a couple of clicks to get all the required information (including precision as someone else mentioned).