Corruption said:
I'm looking for orchestral scale and impact
Good on you

. I'll answer accordingly.
Vaughan-Williams - Thomas Tallis / Greensleeves
Try some of VW's symphonies. These days it's usually easier and cheaper just to buy a box set of all 9 (usually about 7 CDs for around £15ish) - you could start with the 2nd, 3rd or 5th, none of which are too far away from
Tallis or
Greensleeves stylistically.
There are dozens of other pleasant enough Vivaldi fiddle concertos too, but I'd be inclined to look elsewhere. Make it a priority to chase up the Bach violin concertos (there are three, and you usually get them all together - A Minor, E Major, "Double").
Corruption said:
Respighi's "Roman trilogy" is reasonably similar in a lot of respects (three works:
The Pines of Rome,
The Fountains of Rome,
Roman Festivals). [A lot of Holst's other music is worth hearing, but it's mostly not that much like
The Planets.]
Corruption said:
Ummm, the thing here is that
Bolero is a real oddity - there's really nothing very much like it. I could point you in the direction of Ravel's left-hand
Piano Concerto or
La Valse, both of which are great and would fit your stated requirements, but neither of them bear much resemblance to
Bolero.
I suppose you could try something like John Adams'
Short ride in a fast machine, which - it could be argued - is a distant relative of
Bolero.
If you try any of the above, let us know how you get on - if you hate any of it, let me know what and why and I'll try to suggest something else.