If you treat the earth as a uniform, water-covered sphere, computing the height and timing of the tides is fairly simple -- it was tackled by Laplace in 1778. The gravitational attraction of the moon is stronger directly under the moon, pulling upward on the surface of the ocean. The moon's gravity pulls more weakly on the ocean facing away from the moon than it pulls on the rest of the Earth -- so when viewed from the solid Earth, the ocean there appears to be pushed away from the moon. The tidal bulges that result stay fixed as the Earth rotates under them, resulting in two high and two low tides per day. Tides will be highest at the equator, and zero at the poles.
However, the Earth is not a uniform, water-covered sphere. There are continents, and the bottom of the ocean varies in depth. This topographic variation causes the tidal amplitude differences you describe.
Take a large bowl, put some water in it, and give it strong push so the water sloshes back and forth. Note that the sloshing is largest at the rim of the bowl at the location adjacent to and directly opposite from the place where you bumped it, and there's a "nodal line" where the sloshing is zero. You can also push the bowl around in a small circle: when you do this, the nodal line rotates around the bowl, with zero sloshing at the center. Your hand pushing the bowl acts just like the moon's gravity, and the response of the water in the bowl resembles the tides sloshing around in the ocean basins.
There's a special frequency at which you can push the bowl back and forth which will cause the sloshing to get extremely violent. This frequency depends on the size of the bowl: big bowls have lower frequencies. (When I was little, I used to do this in the bathtub, and splash all the water out.) This is called the basin's "resonant frequency".
Go to the seashore and watch the waves. You can see that as the waves come onto the shore, they get taller and steeper, until they fall over and break. The tides are just very, very large water waves, with heights of a meter or two and wavelengths of thousands of kilometers. When they come onto shallow water, they get taller, although they never get steep enough to break.
Waves entering a channel which gets narrower will be "focused" by the walls of the channel, and all their energy will be compressed into a small space. This makes the waves larger. Tides do the same thing: narrow bays, fjords, and channels often have the biggest tides.
Actually figuring out how all these effects interact and predicting the tides is impossible to do by hand: one must build a complex computer model of the oceans. This web page shows figures from such a model (which also has satellite observation data mixed in). You may find figure 2 most useful. The colors show the amplitude of the tide: the lines show how the "nodal line" of zero-height changes with time. The "M2" is the common twice-daily tide: the "K2" tide shown is at another frequency (once-daily, I think.)
Notice that tides are fairly large at the equator, as the "whole-earth ocean" model would predict. Note also that, just as with the bowl experiment, the tides at the centers of the ocean basins are generally weakest. Note that at convergent bays and channels, like the Labrador Sea, North Sea, Gulf of Alaska, the Mozambique Channel, and Weddell Sea, the tides are large due to the "focusing effect" I mentioned earlier. Tides are also high in shallow areas like those near Great Britain, and New Zealand. Tides are generally small in the Mediterranean Sea.
Giving a precise answer to your question is hard, but I believe that Belgium has large tides because of the focusing effect of the North Sea and the English Channel, and because of the shallowness of the sea there. Teneriffe, on the Canary Islands in the middle of the Atlantic, has small tides because it's near a "node" of the sloshing. Nice probably has small tides because the Mediterranean is so small that its resonant frequency is much faster than the twice-daily "push" given by the moon.
Also, I believe that the tidal velocities are very large at the mouth of the straits of Gibraltar, but I learned about this at a long-ago-forgotten seminar, and can't give you a source for this information. However, the tides there aren't enough to "fill up" the Mediterranean, and the Med Sea sloshes like an isolated "bowl".