More info needed.
You say "...building a small collection..." does that mean that you yourself are making the knives, including the blades, or that you are assembling blades with your own handles, or that you are working on a collection, but not actually making the knives in it yourself?
Are you looking at full tang, or hidden tang?
Stainless or carbon steel?
If you are making or assembling yourself, what tools and experience do you have?
What is your aim? Is it that you want different sizes and styles for you, or are you making a batch for gifts and want everyone to have something unique? Are they intended to just look different, but all on the same general format, or are they meant to perform different tasks?
We can give what we think is advice, based on your opening question, but its pot luck whether it is good advice for you. Providing more info for us to go on will get you better advice.
Liners:
Vulcanised fibre, sold by knife making suppliers, can absorb water and increase the chance of rust on exposed full tang edges. Thin G10 is better in this regard, but the colours can be a bit different, the red isn't as bright for instance. G10 is also harder to source.
Woods:
Some are lighter weight (birch, walnut, yew, cherry, ash), while others are oily and resist moisture (cocobolo, bocote, bubinga, rosewood, blackwood, kingwood etc). Some take oil finishes well (the light woods+ maple), and others, not so much (the oily ones mentioned + others like Thuya). Many look great, but are soft (some birch and walnut, thuya and many things with burl patterns). Then there are all the acrylic resin stabilised versions, stable, moisture resistant, but heavy and more expensive.
Lots of woods create dust that isn't great to breath, so a good dust mask is a good idea.
Good starting place would be:
http://www.english-handmade-knives.co.uk/acatalog/Wood_Blocks_for_Knife_Handles.html
These are some that I did, years ago, but shows a variety of wood.
IMG_4850 by
Last Scratch, on Flickr
To see what woods look like, you could spend time just looking at these sites. Not practical to buy from, unless you are very serious, but good info and great pictures for an education:
https://www.gilmerwood.com/categories/39-new-arrivals/products
http://burlsource.us/
http://greenbergwoods.com/