If your just hooking up a monitor most are probably using the DisplayPort for that with a DP to VGA adapter. Google Displayport to VGA.
Edit: as Hughlle mentioned the connection on the SP3 is a miniDP, be sure to get the right one if you go this way
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Although you could use a USB DisplayLink to VGA adapter these use more CPU resources.
If your making other connections then docking stations are convenient. You have two choices:
The Microsoft Dock or a USB Docking station. the MS Dock is physically larger and more expensive and may have some quality issues. USB Docks are cheaper and smaller but use DisplayLink technology which uses a little more CPU resources. The USB Docks are available with one or two monitor connections with a variety of connections VGA among them.
Google DisplayLink Dock. look for a USB 3.0 version.
A USB 2.0 will work you wouldn't have any higher speed USB 3.0 connections.
The Pluggable UD-3900USB 3.0 docking station is popular. I decided on the Targus version because it lies flat.
