Just started to build a new layout for the grandkids and I nee some advise.
it is 5X8 here is what I am think of please give me so advise. Here is a link to phothbucket
thanks
Roadie,
I checked your plan and I noticed that the radii of your curves are very sharp in the beginning of each curve. I guess you have used RTS to draw your plan. The flextrack feature is a little tricky to operate. If you want me to help you, just send me your RTS file via “contact” and “e-mail”.
To post pics from photobucket simply click on the line called image code: it’s to the left of your pic. Then right cilck and select paste while posting a message. You get this as a result: 
Welcome back to modelrailroading and to the forums.
Much has changed in the last 30 years, I suggest you read up on some of the new scenery and electronic ideas.
Before you go too far, have you concidered other types of layouts? The design you have shown has to be an island, so you can get to all sides of it. (30" reach maximum is recommended, due to scenery, buioldings, etc. making it harder to reach through/over than a flat table.) What type of space do you have available? Around the room shelves are popular now, out of the way and reachable if you use a 1/2 sheet of plywood or 2x8 extruded foam.
(Got interrupted, now where was I?)
Since you are building it with your grandchildren in mind, I expect you don’t want it to be to complicated, but something that you can add to as they (and you) get more skilled. For a plan like you have shown, I think I would concider DCC. I haven’t used it except on a layout I visited, but am concidering it for my large layout that is in the planning. Saves a lot of switch throwing, especially with younger ones both running trains at the same time.
I know you want to get something running to get and keep their interest. You can do that on a small layout, either a temporary one or a loop on your large layout. They can work with you as you add more track, scenery and detail. As everyones skills improve you can go back over an area and redo it. Many folks here indicate that they have done that. Even changed whole scenes, when one looses interest or something new of more interest comes along.
Have fun,