Using Saxophone and Euphonium in Orchestral Works

Lately I've been toying with the idea of including saxophone and euphonium in some of my orchestral works. I'm interested in not only using them as solo instruments, but also using them as more integral members of the orchestra, i.e. blending them with other instruments of the ensemble to create interesting textures. Do you guys have any suggestions for works that showcase these instruments in an orchestral context? Also, if you have any experience using these instruments in orchestral works, do you have any advice or wisdom to share? There is of course plenty of works for band with these instruments, but I'm wondering if there are good examples of these instruments blending with strings.

I found a couple of suggestions from Wikipedia for Euphonium and Saxophones. A couple of notable ones I'm familiar with:

Euphonium: The Planets (some good blending with strings in this piece), Ein Heldenleben

Saxophone: Shostakovich's Suite for Variety orchestra (shows both solos and blending with strings), Bolero, Pictures at an Exhibition

Any others, or any advice for using Euphonium/Saxophone in orchestra? 

Edit: Also, do you recommend any sample libraries with good sax/euphonium sounds? Currently looking at Vienna Symphonic Library...

One of my favorite sax examples is Britten's "Sinfonia Da Requiem". There's also the obvious Prokofiev Romeo and Juliet and the Vaughn Williams Symphony (I don't remember which one).

Why not, if the timbre seems right for the work you're composing?

As I still consider I write orchestrally but with the likelihood of live performance diminishing by the day I apply instruments that some would think unusual. They'll stay in a "virtual" performance although the instruments are available to most orchestras.

In a recent piece I substituted the 4 horns and a trumpet with 4 Wagner tubas and a flugelhorn as being a little mellower in context. Likewise saxophones that seem to be treated as woodwind in pieces with which I'm familiar - Vaughan Williams' 6th and 9th symphonies and a fair few works by Villa-Lobos.

Blending the instruments in would probably follow the same issues as balancing any other woodwind with the rest as far as I can see.

@Monarcheon, @Quinn, thank you for your suggestions! I just listened to Vaughn Williams' Symphony No. 9, which has 2 alto saxophones and tenor saxophone, and uses them quite extensively as integral members of the orchestra. To a large extent they seem to double the horns, but there is quite a bit of doubling with the other woodwinds and even the strings, which adds quite an interesting texture. 

I will also check out some of your other recommendations as well!

You can use "Berlin Brass" by Orchestral tools. And my advice for scores on melodies is here https://musescore.com/sheetmusic?text=Euphonium   

In most of my works for a larger orchestra these days I ask for a contrabass clarinet as opposed to a contrabassoon as the clarinet can play it's lowest notes miles quieter than the bassoon. (I also mark the part as playable by a solo double bass if a contra-clarinet isn't available. Obviously far from the same timbre it can 'fill in' the very bottom of the harmony. It's rare but possible to get a contrabassoon solo. Likewise one for contrabass clarinet. If it does happen and a double bass is substituted the difference in timbre will just have to be suffered!)