Instead of buying furniture for short-term needs, Cotter's clients are investing more and using quality products and good fixtures and finishings. They are also now putting much more thought into these furnishings.
In terms of colour trends, Cotter believes New Zealand homes don't have much wall space left, so stronger colours on walls, and darker-coloured walls, have become a real interior design trend. But, if using dark colours, pops of contrasting colour in furnishings is a good idea.
"Architects love giving us wonderful windows and sliding glass doors to create indoor/outdoor flow, which takes away walls and also lets in more light," says Cotter.
"LED Lighting has also let us use darker colours on the walls as the whiter light bulb means we can enjoy colour in the home again, rather than it having a yellow tinge of traditional artificial light sources. Open plan has also taken away walls, too."
Open plan is here to stay and very much part of modern home style, but interior designers and architects have gotten better at hiding clutter associated with living, dining and kitchens combined in the one space.
"We're working more with butler's pantries and visual screening, so your world isn't completely on display," says Cotter. "We're also seeing architects play with levels again in new builds, that's a trend coming back around in things like lounge spaces, where you slightly step down into it as a point of difference."
And if you thought minimalist Scandinavian styling was here to stay, get ready to adapt to a softer design style.
According to Cotter, the harshness of the Scandinavian feel is being warmed up with more fabric, more textures and adding more natural timber to the overall design aesthetic.
Bohemian styles are gaining in popularity and Cotter describes the style as "more collected, encompassing a little bit of personality from your travels".
Rather than the trash-is-treasure feel, it's more eclectic, yet still curated and a way of pulling together your pieces to tell a story. The leader of the pack in this style is designer and artist Justina Blakeney, who is the author of New York Times bestselling book The New Bohemians.
"I'm a great believer that if there's a history behind what you're purchasing, then it's a future-proofed purchase as you have an empathy towards it," says Cotter. "If you hold it close to your heart, then you're less likely to throw it out."
The market was flooded with copper tones in every kind of decor accessory, so people have stepped back from that a little, but dark silvers, pewter and zinc are still going strong. There is also lots of metal framed furniture hitting the market, such as black metal legs on coffee tables and sofas. Sonya Cotter, designer
Stronger, darker-coloured walls, have become a real interior design trend; Zinc pieces like this table and vase (below) bring out a modern, industrial feel.
Metals are another interior design trend that is here to stay, and they include copper, bronzes and zinc.
Cotter says they started out by bringing out an industrial feel but an adapted 'cosy industrial' design has made them softer and metal with shiny brass has also kept the trend moving forward.
"The market was flooded with copper tones in every kind of decor accessory, so people have stepped back from that a little, but dark silvers, pewter and zinc are still going strong," says Cotter.
"There is also lots of metal-framed furniture hitting the market, such as black metal legs on coffee tables and sofas."
The internet is opening up information and ideas, so a collective New Zealand style is less prominent, as international styles are sourced by New Zealanders on Instagram to create mood boards for their rooms.
However, Cotter warns that jumping on a design trend does have to be done with a certain restraint and only if it works in with the overall design concept.
She says decor accessories aren't too expensive, so trying out the trends in the smaller way means they are easy to change later.
"Have some fun and if you love it, do it," suggests Cotter.
Marble has been a trend for a while, but what's new is black marble for a change to the grey-and-white marble that was used in many decor accessories and benchtops.
"The popularity of marble has really opened my client's eyes to stone and granite, which also has quite a lot of movement," says Cotter.
"A few years ago, it wouldn't have been an option, but clients now want things with a bit of personality and lasting power."
Textures are also being used in new ways, such as concrete with a shuttering effect where timber imprints are left on the concrete panels, giving the effect of wooden beams.
"Natural products and interesting textures are definitely around to stay," says Cotter.
"It's all about celebrating nature in its true form and that's something that is continuing to progress."
"Textures such as velvet and chenille reflect light for a shimmer and sheen, as opposed to natural linen that absorbs light," says Cotter.
"There's a quality to the new fabrics and textures coming out, such as weaves with different tones within them or flooring that revisits loop pile carpets - we haven't see that for a while. These textures are pretty stunning and add a design difference to create interest."
Overall, she says that with most things we use being shiny and glossy - such as phones, tablets and cars - our fingertips are desperate for a little bit of texture and touch and the home is where we're looking to find it.
So, if you look for items that give you a sense of nature and texture, you should be ahead of the pack.