Having been blown away by the Californian Redwoods on the Rhinefield Ornamental Drive in the New Forest and in the Peebles area of Scotland, as soon as we had a garden large enough we purchased two redwoods and planted them in the middle of the garden. This was in 2008 and we then proceeded to build the rest of the garden round them. We planted them to what I am assured allows for the width they will eventually become, although I suspect we will have to cut an archway through them, if we want to be able to continue to access the orchard through the existing arch!
We positioned the summerhouse so that they will provide some shade on the hottest days. If I'm honest, we didn't really think this one through but there are plenty of other areas we can sunbathe in, in 10 years time, when there probably won't be much sun at the summerhouse at all. South is the direction behind us, so the only thing they will provide shade for is the summerhouse which give us plenty of apples and pears for the scrumpy as the orchard develops.
I have now dug a decent border for them and underplanted them with dwarf echium raised from seed and forget-me-nots transplanted from self-seedlings, for the bees to enjoy. We have honey bees for the first time this year and a bumblebee nest under the summerhouse decking so a few more bee friendly plants won't go amiss.