Not sure how many people are aware (or not) of how powerful the CTRL key is, but thought that I'd post a TIP. Even if only one person thinks "Darn, I didn't know that" then it's worth it.
Typically the CTRL key is used to highlight multiple objects to perform a move or similar function. However it can be used to make multiple edits quickly.
Say for instance that you have a existing plan and you don't want to show sizes for any openings. If you CTRL-CLICK away from all objects, and marquee select everything, then RIGHT CLICK, you get a list of all the highlighted items. Pretty standard so far .... Now go to OPENINGS on the list, and click REMOVE SELECTION. Now everything except OPENINGS is selected. Now if you CTRL-CLICK away from all objects, and marquee select everything again, it will actually reverse the selection, so that only OPENINGS are selected. You can then RIGHT CLICK, go to EDIT & REPEAT and uncheck display size, and ALL the openings will change in one go.
You can also use the same methodology to remove GRILLES and EXTERIOR TRIM etc., cleanup extension lines and SET LAYERS, CHANGE COLOURS, STYLES and THICKNESSES of SHAPES etc. and pretty much any function that you need to perform on multiple objects. Can be much quicker than REPEAT EDIT.