I've already narrowed down my options for the new layout. Basically, I decided that it would be silly to start from scratch after all the time and effort I've put in to coming up with and fine-tuning it over the past few months. I have pretty much got a mental picture of every part of the layout so I'd prefer to build on that.
By taking advantage of the extra space I would have, I can afford to space things out slightly more - not hugely, but enough to overcome one or two sticking points with the original plan. I would increase the width at the station end of the baseboards to 2' 6", narrowing to 2' 0" at the half way point, effectively adding another 6-9 inches depth to the entire layout. This would help in the goods yard, allowing me to keep the bay platform and still have space for two goods yard sidings, including a proper goods shed.
For the rest of the layout, the additional depth would allow for more in the way of scenic interest - creating a better impression of the railway on the landscape.
Lengthways, the extra 2' available would enable me to do a couple of things - 1) lengthen the 'off-stage' area to 4' allowing for slightly longer trains if required, and 2) increase the length of the station and goods yard area by another 6-8".
However, there is another possibility whereby I could quite significantly increase the running length of the layout and create much more of an impression of the railway running through the lanscape. This is to create a large curve (approximately 4' radius but with a transition into it) leading from the existing exit point, left (if travelling out of the station) round the end wall of the garage and into a 4' long straight beyond that where the 'off-stage' storage area would be situated.
This would create about another 5' of running line before the exit point, with additional scenic potential.
The only drawbacks with this would be the extra, corner baseboard (and support) required. Aside from that it would only be single track so no extra track-building as such would be required, just ballasting and scenery construction. Also possibly even with a 4' radius curve, this may seem quite tight, visually - indeed it is much tighter than any prototype passenger line would be. The curvature could be disguised slightly by careful placement of trees, bridges etc. and also by the use of a gradual transition from the straight section into the curve.
Because I will have to scrap my existing basebaords and start again, and also because of the additional depth, I think I will make each board smaller widthways (max 4' wide), and have more of them, so as to maintain some level of portability for the future. Other considerations will be whether to have some sections open-topped to allow for landscape below the level of the railway and also decrease weight, whether to use a smaller profile timber for the frame (again to help reduce weight), and making sure I plan where the baseboard joins go based on the track plan rather than (as happened previously) trying to squeeze the track plan into the restrictions of the baseboards (to avoid point work on joins etc.).
Another question is how to support the baseboards. With more depth, the bookshelves currently being used may be too narrow leading to instability, so I may need to look into building a simple structure of legs. Ideally I'd like the basebaords to simply sit on top of a rigid structure so that they can if required be removed individually. I need to do some sketching to work out what would be most effective - and also quick and easy to build!
Anyway, I should probably be holding my horses until we know the purchase of the house has gone through successfully! Oh well, its all good fun in the meantime!