Retezat are spectacular mountains, with many peaks over 2000 meters high that remain covered in snow from December until the second half of May and sometimes even longer.
In April, most likely it will be cold, windy and inhospitable on the summit, however the nice views along the way and the reasonable steep path will make it a pleasant journey.
The Piatra Mare Mountains are located 10 km south from the city of Brasov. The fact they are not very tall mountains makes their highest peaks accessible all year round. The summit of Piatra Mare Mountains is at Varful Piatra Mare (1844 m).
From Omu peak you will have some nice panoramic views of all the mountains and valleys around. Also, the ascend from Cabana Malaiesti to Omu Peak via the Malaiesti Valley is beautiful as well.
The Ciucas Mountains are close to Brasov and Bucharest and are great for easy to moderate day hikes, all year round. The highest peak in Ciucas Mountains is Ciucas Peak (1954 m), followed by Gropşoarele (1883 m), Tigăile Mari (1844 m) and Zăganu (1817 m).
Ascend from Azuga to Urechea Peak (1705 m) on this 3 hours long moderate hiking trail and you will be rewarded with beautiful views over the Bucegi Mountains.