I prefer leather for many things, but especially for spankers, floggers, crops and such. In a a huge arsenal of these tools I'd say about 95% are leather (including suede here). Wood is great as a material for these, but a bit harsh for my tastes. I am not a faux leather type person, sorry. I do like a good looking chain, and have a remarkably enjoyable chain flogger from AS, so would love to see more items along these lines as Terri mentioned above.
As far as sensory play goes, metal (with no allergens, so alluminimum or stainless or titanium or even silver/gold) is preferred, but glass is very versatile for many objects (other than insertable ones I mean), and wood can substitute a valid choice for nature lovers and/or beginners. I usually avoid plastic in all aspects of my life, so I would prefer to avoid it here too.
As far as restraints go, I hate velcro and the likes. Again, either let it be leather, or chains or some kind of fabric (polyester might do) - but for me elegance and style are crucial for all these toys, so cheap looking like nylon would probably not get bought. I actually prefer the "soft" bondage labeled restraints (such as "satin"), as they are usually more in line with this requirement of mine. Comfort and no lasting signs is a must also.
As far as broadening LH's offer, wow, would I have many-many ideas without going into the extreme as you asked. As an international buyer I am limited in what UK retailers I can (as in it is worth to) buy from, but there is a U...k...y named competitor that has a few bits I really want. Having not had answers on my product requests on the Pander to me, I am very close to buying from them now... There is one cheapish heated metal wand for one, a silicone stand-to-pee cup for ladies, a scrotum cuff that is quite intriguing, a few detailed books about different aspects of bondage such as flogging, spanking, waxing, etc., they also offer more ball stretchers, a realistic ball sack for toys, a great variety of wand attachments... the Bondage Man rainbow pack is also to die for! I am also one that enjoys symbolic "fun" items in bondage too, such as the hand paddle they offer. I find LH's current offer too "serious" at times and having now bought almost everything I would be interested on here, I am - in lack of a better word and I apologise in advance for my frankness - bored by most segments of this site lately.
As far as colours go, I might be obvious, but I am an "all black" girl, and I do like to spice things up occasionally with intense red shades - especially if we are talking about bedroom activities. I would consider burgundy or dark green or maybe grey, but definitely not bright or pastel colours.