I too use Excel for my O Gauge and G Gauge collections. I track Part #, Road Name, if it is Rolling Stock, Building, etc., Type of Equipment, Description, Manufacuturer, Car #, purchase price, place of purchase, year produced and comments.
Yes, Excel is easily resorted. It remembers the sort criteria from the last time you sorted data.
The other great function I use is the Auto Filter. Auto Filter puts a drop down arrow in your Column headings. Click the drop down and you can choose any entry to filter on. For example in the Equipment type column I enter, Loco Steam, Loco Diesel, Box Car, Reefer, etc. If I want to see just my box car collection I click the drop down and choose Box Car. Excel then filters out all other data so my list only shows Box Cars. You can set multiple filters at one time. Just remember that the filters are on when you are looking for something that you can't find.