Melissa, sounds like you have a typical Mediterranean climate, which is what most of the west coast of the US enjoys, particularly California (more northern parts, like the PNW, are considered a modified Med climate). Soils vary widely over this area but clematis seem to do equally well throughout, provided good drainage is available. They dislike being dry in summer and would appreciate regular deep waterings and will perform and thrive much better if they receive them at least occasionally.

I have yet to find any variety of clematis that will not thrive here except for the few not fully hardy and C. florida 'Sieboldii', which for me has been extraordinarily fussy. Certainly all the species you list and the closely related hybrids have done well for me. I tend to grow less type twos than others but only because those included in pruning groups 1 and 3 interest and appeal to me more.

The only changes I would suggest you make is to make sure your planting sites are well-amended with organic matter, both to loosen the heavy soil, improve drainage and assist with moisture retention. And mulch well during the summer months to conserve whatever soil moisture exists. And if you can, give 'em a good long drink every so often. Otherwise, I don't think you need to limit your choices -- try whatever you fancy :-)

I would suggest that the texensis and viticellas would be the ones to avoid shade. Many of the large flowering hybrids will tolerate some shade though. Root competition has proven a problem for me as well.

If you're in Northern Italy near I Monti Appennini (Le Marche or further west?), then you live in an area where C. viticella is indigenous. The viticellas and viorna group (including texensis and its hybrids) grow naturally on the edges of sunny forests or brushy areas. So keep these in as much sun as possible - they tolerate extreme heat (viticellas are found as far south as northern Africa, texensis from Texas, USA) and, once established, can tolerate some dryness.

Integrifolias and its hybrids are from similar regions in the Mediterranean, and will be just as bullet proof if given adequate sunlight. These 3 groups do not perform as well in shady areas, though you will still get some blooms.

Tangutica and its ilk can tolerate extreme heat and full, hot sun, but will rot and die during wet winters. If you're in Le Marche or Piemonte, these may not be the best choice unless you cover them with plastic/glass in the winter.

Alpinas and macropetalas do not like extreme heat too much, and most importantly can die off if not kept well watered during hot summers. The tubulosa group, however (C. heracleifolia, et al.) are perfect for hot, dry, sunny sites once established.

The patens group (The President + other early types with large blooms) can tolerate some shade quite well, but prefer even moisture during hot summers. As has been stated, root competition can kill a clematis, especially without additional water during the summer.

Also indigenous to the Mediterranean would be C. flammula and its hybrids, which love hot, dry weather and C. recta in its various forms.

Viticella and Texensis hybrids and cultivars; pruning class II hybrids; C. alpina and C. macropetala, and do they have similar requirements?; C. heracleifolia forms and hybrids; C. integrifolia forms and hybrids; C. tangutica; and others. As you can see I'm ready to wallow in clematis starting this fall, but it would be helpful to know of any things absolutely

Gardengal, Buyorsell, Michael,
Thank you all for your comments! You're all giving me the impression that I can grow a lot of kinds of clematis, and that's what I love to hear. Buyorsell, "shade" here is in the context of a hot sunny climate. I follow your argument, but actually my best performer in the (so-called) shade garden has been 'Mme. Julia Correvon', a Viticella cultivar. I'm always suspicious about vining plants that are supposed to require full sun. The shade garden is actually half sun, and as I said many roses that like a cooler atmosphere do better here than out in the more exposed sunny garden. I do have one Texensis cultivar that looks perpetually starved and put-upon, and I would like to try it in a sunnier position, because those Texensis hybrids are just too pretty. Michael, thanks for your comments. I live in the hills in the province of Piacenza. I didn't recall seeing Clematis viticella around here (as opposed to C. vitalba which is everywhere and horribly invasive), so I checked my 'Flora Piacentina' and in fact C. viticella isn't found wild in the province; the only native Clematis species here is C. vitalba. I don't know what C. viticella's native range in Italy is. I have C. integrifolia down in one of the sunnier spots in the shade garden, with old roses and herbaceous peonies, and like them it's doing fine. The environment is the edge of a woodland, which I find a lot of garden plants like. I rarely have problems with drainage, because of our steep slope. Let's hope that C. tangutica will be happy under these conditions. I believe my sister told me she grew it in western Washington, which is certainly wet enough in the wintertime. It sounds like C. tangutica would do best at the edge of a drop, though. I've had C. alpina in my garden, in some of the shadier spots, for a couple of years, and it does pretty well. Even though we have hot summers, the air is dry and temperatures drop at night. I have an idea that plants that suffer from summer heat do so in humid summer climates where the air stays warm twenty-four hours a day. I'm happy to hear what you have to say about C. heracleifolia, and am already thinking about hot sunny banks in the garden, of which I have many! About clematis and watering, I'm sure that the large-flowered patens hybrids appreciate summer water where they get it, but they can manage without once they're established: mine do at any rate. This may owe much to the considerable depth of clay in our garden, to our abundant spring rains, and to the permanent hay mulch. After the first year I lose few plants to drought, even though we don't water. I know I sound like I'm contradicting much of what you've said. It's not out of perversity, but I've gardened for years in both the U.S. and in Italy, and have been able to see how the climate differs here from that of the eastern U.S. and the Midwest in particular.
Again, thank you all for your comments; I appreciate your taking the trouble to respond.
Melissa