Thanks for all your different suggestions. We have decided to have an extra suitcase shipped to our London hotel, using Shipgo. This will give me a chance to take some of the additional items I would like to have on our ocean cruises. We have taken 30 plus ocean cruises, and I enjoy having a variety of clothes. I have always taken 2 suitcases for myself when we travel abroad. We use porters and normally haven't had problems dealing with the luggage.
With our Avalon River Cruise restricting us to one large suitcase each, I knew I had to find a way to take my second suitcase, so shipping it is what I will do.
Thanks again for all the great ideas!