The last game in Bundesliga is no longer important for Leverkusen and they even can sacrifice it, lose it to aim at two bigger targets, two titles in Europa League and DFB Pokal cup.
Every match is important for Leverkusen if they want to keep the unbeaten record. I think they can do it, they don't need to play 100% because they are not playing a strong team in the final match of Bundesliga.
Being unbeaten in Bundesliga is impressive but if they have to pay it with cost of key player injuries, it does not worth to pay. Two titles in Europa League and DFB Pokal will be enough to make this season as a most successful one in Leverkusen's history. If they end Bundesliga unbeaten but won't win two titles in Europa League and DBF Pokal, it will make this season is not too successful for them.
Having the unbeaten record in the whole season will be a great achievement. I think it is worth fighting for the record, Leverkusen may have no chance to achieve it in the future. Why don't to try winning the match? Leverkusen has many players in their squad, they can use the second tier players to play on the match. So, it won't be a serious problem for Xabi to win the final match in Bundesliga.
Atalanta are ready for the final match with Leverkusen by a preparation in Serie A, beating Roma in a direct match and secure their fifth position. They will highly be qualified for Champions League with the fifth position and will aim at the final match with Leverkusen very confidently.
Of course, Atalanta is a strong opponent in the final UEL. They just beat AS Roma in Serie A, it may give them a more motivation to play with their best in the final UEL. However, I think Leverkusen should know how to deal with Atalanta. Xabi Alonso is a smart coach, he knows a proper tactic to destroy the strong defense of Atalanta. Since Leverkusen has everything to win the UEL final match, I no doubt to favor Leverkusen for the champion.