The spice in the rye goes well with the herbal elements of the St. Germain and bitterness of the Aperol.  You can cut the St. Germain down to 1/4 oz, but you will need to reduce the bitters as well.

• 1 1/2 oz Rye Whiskey
• 3/4 oz St. Germain Elderflower Liqueur
• 3/4 oz Aperol
• 1-2 dashes rhubarb bitters

I think Peychaud’s Bitters were made for rye whiskey.  I tried using simple syrup, but I did not like the additional dilution.  Also, don’t skimp on the bitters.

• 2 oz Good rye such as Sazerac or Bulleit Small Batch
• 1/2 – 1 tsp Sugar
• 3-4 dashes Peychaud’s Bitters