Yesterday I looked at five GPS features you don't need. Today we'll check out the flip-side; what are the best and most useful upgrades when choosing a navigator? I'll start with ones available on relatively low end units and then move on to features found on more expensive models.

• Text-to-speech - Abbreviated as TTS, this feature calls out street names for upcoming turns. Which means that you'll hear "drive one-half mile, then
  turn left on Oak Street." instead of just "drive
  one-half mile, then turn left."
• Wide-screen - A 4.3" touch screen is just so much nicer than a 3.5" model. It's easier to tap menus and keypads without error, and the map display isn't as cluttered.
• Points of interest - Abbreviated as POIs. Some cheap units have as few as 750,000 POIs; you may as well just give up on finding anything without keying in an address. I strongly recommend getting a unit with at least 4.5 million. This is one reason I like Garmin units — they don't short-change you on POIs on low-end models; you'll get nearly 6 million on any of their units. TomTom just says that they have "millions of POIs," but I've never really found their units lacking. Even with one of these two leading brands, you'll still have plenty of places that aren't in the POI database, but you'll experience it less often.

If you can swing it, I highly recommend the above upgrades. The next three may not be as critical, but are still worth paying extra for. You can get them on cheaper models, but it will sometimes mean getting a second-tier brand and/or one with weaker implementation of the feature.

• Multi-destination routing - Allows you to pre-plan a trip with multiple stops. The better units do a good job of "optimizing" the order of the stops for efficiency; they also automatically advance you to the next point on the route.
• Lane Assist - Gives you visual guidance as to what lane you should be in for turns. This can be very helpful on freeways or on urban streets with multiple turn lanes. Coverage is usually limited to major metropolitan areas.
• Speed limit display - Helpful if you have a lead foot; it will more than pay for itself if it keeps you from getting a single ticket. The ideal implementation will show your current speed on the map screen as well, or allow you to set an alarm if you go a certain amount over the speed limit.