I use a ring lock that is attached to the frame to lock the rear wheel to the frame. As it is a relatively cheap second hand bike (€200 4 years back) that is how it is locked unless left for a long time or in a dangerous place.
When I lock properly, the long cable lock will go through the front wheel, through a smallish hole or loop of a fixed object and either around the bar of the middle of the bike or through any of the 'loops' that the frame of the bike has. As I expect bike thieves to be mostly opportunists (where and when I park) I expect two locks to be enough in most or all occasions.
My friend, who owns a much more expensive 'bent bike, uses a better lock but basically uses the same method. The hard lock is on the bike itself, it is the expensive cable that holds the bike in place.
In places where I would not trust that kind of locking, I would not leave my bike. All locks only slow the thieves, never stop them. Ratings should give 'minutes' or even 'seconds' delay. And then, even the best locks can be dealt with in seconds if the 'right' tools are used.
If I had to lock my bike with an U shaped lock, I would try to get the front of the bike to the fixed object, so the lock goes about the bar between front and back as well as around the fixed point.
Locking the trike is even less a problem but more of an annoyance. As I had an insurance on it, I had to use a heavy chain, other approved locks did not fit the trike. With that chain I can fix one of the 'loops' of the frame, one rear wheel and a fixed spot. I still have a cable lock for the trike, which I can use to lock both rear wheels to the frame and to a fixed point, or I can use it for the front of the trike. But the frame of the trike has all kinds of 'loops' that make locking it easier.
Bike Batavus Relaxx: http://hpv.popol.eu/pix/relaxx.jpg
Trike looks very much like a Sun EZ3USX: http://photos1.blogger.com/blogger/6278/3190/1600/EZ3%20USX.4.jpg
I am living in the Netherlands where bike thieves are almost as common as bikes but most thefts are done to get to places on the 'borrowed' bike. Having an uncommon bike is a help there, thieves will not know how to ride it and it will stand out.