GadgetGirl,
I have a Rino530HCx and ran into the same issue myself. As you have discovered from previous responses, its possible to select which map you want to display.
For future reference, I found the text below in one of my manuals. It describes the hierarchy used to display overlapping maps. I looked in the manual for the 60CSx but it wasn't there. No wonder you were having problems . Hope this helps.
Transferring MapSource Data
If you have purchased a Garmin MapSource Data program, you may want to transfer detailed map data before beginning use to provide your unit with maximum Find features and mapping capability.
You cannot view multiple types of MapSource data in the same location at the same time (one replaces the other if there is an overlap). When you leave a CitySelect area for example and enter the area of a topographic map, the display changes to contour lines. The same is true when moving from a topo map to a CitySelect map. The BlueChart maps are at the top of the hierarchy and will replace any other map information. Here is the list of the hierarchy for your reference:
1. BlueChart
2. City Select
3. Metro Guide
4. Fishing Hot Spots
5. Points of Interest
6. U.S. Waterways & Lights
7. U.S. Topo
8. Roads and Recreation
9. WorldMap