Oooh MORE garden structures... I'm incredibly jealous! I can't seem to erect the first of a gazillion garden structures that are on the list of 'things I really really want help with'. What's your bloke doing this weekend?
Now then climbing things for your new arch... It all kinda depends on the size of the arch (how much headroom) and it's position (how much sun).
Although a quintessential cottage favourite, Wisteria will swallow the arch and engulf the house before you can google how to prune it properly. It grows into a creeper with a trunk and branches like a tree. Not for your lovely new arch.
Honeysuckle - Noooooo! For much the same reasons as given for wisteria minus the trunk bit. Common Honeysuckle is on the NZ naughty plant list so it would be imprudent to plant this. There are lovely hybrids available in shades of muted lemons and apricots. Gorgeous things but I'm terrified that when I'm sleeping it'll be off raping and pillaging my garden. BUT... I saw a very neat idea on TV that I am absolutely going to try. Standardising the honeysuckle so it has a straight 'trunk' and a cloud of viney bits arching from the top. Kept under the ever watchful eye of a sharpened pair of pruners, the scented flowers could be enjoyed safe in the knowledge the plant is unlikely to run away in the middle of the night.
Clematis - I have a weird fascination with these plants but you are right they are steeped in mystery when it comes to growing them well. As a result I view those that have gorgeous flowering hybrids cascading over walls and entwining with roses as gardeners with some kind of magical powers. But I am going to have a go this year. A Naiobi (deep velvety black-red) is planned for near the pond. But I digress... Yes clematis would be a lovely choice, but do not get one of the Montana types. Don't be sucked into the blurb that says robust, evergreen, and carefree. What they really mean is this plant will grow at an alarming rate and become a menace to your neigbours. Think Old Man's Beard with pretty flowers. The decidous, winter dormant hybrids are trickier to grow but are SO incredibly beautiful (particualrly as they come in shades of that rare flower comodity, true blue). They have weak-looking flimsy tendrils so your arch is not at risk at being swallowed whole, but alone they look a bit sparse.
Roses - I give this idea two thumbs up! I sympathise with the 'what to choose' sentiment too! I have just made the difficult decision to plant a pair of Graham Thomas' in the front gardens. I would usually choose something a little different and less obvious but when it came down to it GT ticked all the boxes so why argue? To narrow it down you need to fill in a rose questionaire and THEN ask for assistance...
2. Form. Do you like long-budded modern types, flat simple singles, or tight cabbagy old fashioned ones?
3. Fragrance? Personally I think all roses should be as smelly as possibly but that's not everyone's cup of tea.
4. Flowers all season or one big blowout in late spring?
Try to avoid a rambler or any overly vigorous climbers. If you grow a blue clematis (maybe Kiri Te Kanawa) through an old fashioned pale pinky or lemony rose I will be eternally jealous!
And then of course there are other vine choices such as Star Jasmine and trumpet vines and Thunbergias...